It’s no secret: great ideas make the web spin around.

Community-based sites and web applications are rapidly becoming hot property. Young entrepreneurs are making startling amounts of money with simple ideas that connect people and places. Fancy becoming one of them?

The dream is a simple one: with careful planning and some spare time, someone just like you can take a smart concept, add some glitz and make a fortune. But where have all the hot ideas gone? Why are we seeing spin-offs, rip-offs and mash-ups instead of great new concepts? Where are all the rubies in the dust?

It turns out, they’re right where you’re standing. You just need to look a little harder. Here are 11 under-represented site ideas to steal today and make you rich tomorrow. Be quick! The clock’s already ticking.

1. The Reverse Job Board

The mini pitch: “Buy and sell work online.”

What it is: You know all those job boards you see littered around the web? This is a job board flipped on its head. Think of it as a “work wanted” board. Instead of employers posting job offers, this is a place for service providers to post requests for work.

How it works: Designers, developers, writers, and anyone else wanting work can post their request, together with the percentage or fixed fee they’d pay to someone providing a lead.

Why it’s hot: More people than ever are turning to the web as a source of work. Sometimes it’s very hard to find it, or very time-consuming to browse offers and make pitches. Wouldn’t it be great if people could find work for you? And imagine getting paid just for referring someone you know who needs a new website or logo design.

Where the money is: Take a commission when work is successfully placed, or charge a monthly fee to either buy requests or see contact details.

2. Community Consulting

The mini pitch: “Yahoo Answers for website owners.”

What it is: A place where website owners can pay for advice and get opinions from a wide community of experts, dabblers and end-users.

How it works: Website owners use credits to post a screenshot with a link to their site, together with a list of their goals. Community consultants give advice, and credits are dished out between them accordingly. Credits can be cashed in or spent on questions.

Why it’s hot: Opinions and advice are essential to improving your site. This concept would shift the balance from whopping consultancy fees for one person’s opinion to micro-payments and group-thinking. It also puts a value on your own opinions and sagely advice at long last!

Where the money is: Website owners buy credits. Perhaps it costs 25 credits for them to submit their site for community consulting. You could take 5 credits, and get them to spread the remaining 20 between those who respond.

3. Online Debating

The mini pitch: “Wikipedia for arguments”.

What it is: Arguments litter every forum and web hangout. They’re very rarely controlled, and scarcely intellectual, insightful, or conclusive. There must be space for an online debating site that was well-managed and moderated.

The nearest I’ve seen is Squidoo’s “Hey Monkey Brain,” but I’m sure there’s space for more.

How it works: Suggest an argument. Pick a side. Build your case. Encourage the responses of others.

Why it’s hot: Everyone loves expressing their opinion. Your task is to help them do it in a controlled way, and one that you can monetize!

Where the money is: There’s a possibility that people would pay a small fee to start a debate, but it’s far more likely that most of your income would come from affiliate sales and carefully matched advertising.

4. Web Concierge Services

The mini pitch: “Your online butler.”

What it is: Ever wanted to achieve something online, but couldn’t be bothered to spend ages searching around or filling in all those forms to book flights and cinema tickets?

How it works: You make a request by email, text or voicemail to your online butler. It could be anything at all — perhaps, “two tickets for Die Hard 8 at my local cinema tonight”. Your butler dutifully acts on your request. There are automated services that help with this out there already, but an efficient, human-powered offering would stand head-and-shoulders above the rest.

Why it’s hot: Outsourcing and personal virtual assistants are hot topics right now. A market-leading web concierge service could be big business. Think of all the high-fliers, entrepreneurs, and other busy people out there. You could start one service for the super-rich end of the scale as well as one for other busy folks with less cash to splash.

Where the money is: Monthly subscription fees or per-use charges are the way to go here.

5. Live Auction Sites

The mini pitch: “Buy it now on steroids.”

What it is: Online auction sites are great, but few of them capture the same adrenalin rush and buzz that you get from a real auction room. I think there’s still space for a well-executed live auction site that makes listing and bidding super-simple.

How it works: Imagine a list of iPhones for sale — you can only bid on the one at the top, and it’s only available for minutes instead of days. Bids are live and backed by escrow, and when the top item’s been sold, the ones below float upwards and a new item becomes active and open to bids.

Why it’s hot: As a seller, it’s becoming increasingly complicated to list things online, generate buzz, and make a quick sale. A simple live online auction site could solve all that.

Where the money is: Make it free to list and just charge a commission for successful sales. You need to think carefully about how you’ll guarantee that all bids (and items!) are genuine. This could be by asking users to deposit funds into their account prior to bidding, or some other way.

6. Skill Trading

The mini pitch: “Swap skills instead of bills!”

What it is: An online hub to swap your skills for those of others. Instead of paying for services, you simply swap your own.

How it works: Need something doing? Post a “help wanted” ad, together with a list of your own skills and examples of your work.

Why it’s hot: There are thousands of highly-skilled designers, developers, writers, illustrators, musicians and other talented folk littered across the web. But right now, there’s no good way to connect them. Provided you offer a way to mediate any disputes, and ensure that trades are fair and backed by guarantee, a skill trading site could be big business!

Where the money is: Charge monthly fees, or a smaller fee per swap request. Or simply charge for hopeful applicants to get contact info.

7. Speedy book, DVD, game and CD sales

The mini pitch: “Sell anything with a barcode. Fast.”

What it is: Do you have a stash of books, games, DVDs or CDs lying around that you’re not using any more? It seems a shame, doesn’t it? A site or piece of software that enabled scanning of barcodes using a web camera in order to quickly list books could save hours and make megabucks.

How it works: Sign up, scan your books and name your price. Job done! This could work as a website, or it could be a standalone application that linked in with something like Amazon’s Marketplace.

Why it’s hot: Thousands of people have stacks of unused books, games and other items. They’re just too lazy to list them! That’s where you come in.

Where the money is: Take a small commission of book sales. (Or charge a flat fee for the software if you go the stand-alone app route.)

8. A Read It Later Site

The mini pitch: “The web’s reading list.”

What it is: A community reading list for the web. Feed readers are great, but they’re not very sociable, and adoption by non-tech heads is pretty poor. What the web needs is something that everyone can use and understand — an internet reading list!

A site that combines reading, archiving and sharing is long overdue, and would be much more accessible a concept for your technically-challenged friends and family.

How it works: Ever come across a great article, but didn’t have time to read it? You could bookmark it, but you’ll probably forget about it pretty soon. Wouldn’t it be great if you could mark a page to “read it later” and have it stored in an online reading list?

Then, once a week, you could take an hour out of your day and read through everything, tag it with categories, and check out the week’s charts of the most-read items.

Why it’s hot: Feed readers are hot. Community-based sharing of links is hotter. Combine the two concepts for an explosive mix! Yes, there’s a Firefox plugin that does this, but we need something with wider reach.

Where the money is: This is another concept best exploited via advertising. Who says advertising isn’t a good basis for a business model? It’s worked rather well for Google and Digg seems to be doing OK too!

9. A Live House Price Index

The mini pitch: “What’s your house worth right now?”

What it is: A live house price site backed by a powerful data-model, where house prices are overlaid on a map. There are already sites that do this to some extent, and the market is crowded. But if you could put out the first site to offer truly live, by-the-second house prices you’d be swimming in cash.

How it works: The data modeling would be very complex. You’d have to rely on a community-based element to correct your prices, and build a reliable estimation system based on previous house sales, local trends, market effects and the opinion of your users.

Why it’s hot: Every home owner loves to know what their place is worth. For property investors with large portfolios, the opportunity to track the value by-the-second would be incredible valuable. Furthermore, estate agents could probably benefit from a people-powered market index to help with their own sales and estimation.

Where the money is: The possibilities to monetize this concept are endless. Think private house sale commission, affiliate sales, estate-agent and property investor subscriptions, advertising, community ads, and more!

10. Real-Time Public Billboards

The mini pitch: “Your ad anywhere. Right now.”

What it is: A network of billboards, news stands and projectors linked to a single website that allows regular people just like you to place adverts in public spaces. Think of the “one million pixel” site but outdoors.

How it works: You register, upload your advert, choose a location, hit go and see a live webcam feed of your ad displayed in any public space in the world.

Why it’s hot: The cost of billboard advertising is prohibative to most small businesses and individuals. A public, global, mini-billboard network of ads for regular people and businesses that updates at the click of a mouse could earn megabucks. Make it work, and I’m sure Google would want a word with you too.

Where the money is: Simply charge a flat fee or monthly recurring cost to place an ad. You could split your electronic billboards and projectors into small segments, or sell the whole space or network to one advertiser.

11. Website Sales

The mini pitch: “The place to buy and sell websites.”

What it is: If you’ve got an established website to sell, where do you go? There is still no clear-cut market leader in this field. What’s stopping you from filling that gap?

How it works: List your website for sale at either a flat fee or auction rate. Include screenshots, traffic, pagerank and earnings info and watch the money roll in!

Why it’s hot: Domain name sales are big business. But selling a website for what it’s really worth, or buying an online property in a trusted way is still rather tricky.

Where the money is: Take a commission from successful sales in return for offering escrow and listing services, or charge for each listing.