Reverse eBay

eBay (and others) enable people who have stuff to sell it. What about people who want stuff? People that can't find what they're looking for on eBay or the web (super-rare items), or can't be bothered to look? Wouldn't it be great if you could post what you want and the price you're willing to pay for it, and let sellers come to you. After all, they're making money, so they should be doing the hard work.