Now here's an idea: one that I wish I had thought of first. Combine the technology of a wiki (like Wikipedia etc) and the functions of a shopping comparison engine. What do you end up with? Shopwiki. And excellent and interesting innovation to my mind.
So, imagine that you want to shop for something. Should you simply take the word of those who are trying to sell you something? Or perhaps a community populated site, where you can get the advice of those who have actually seen, bought or used the tiems would be better? Well, who is going to tell you more of the truth?
So, for example, look at this section on nursery furniture. You can drill down further to rocking chairs, to changing tables, to toy chests, whatever is your specific desire.
But over and above this great functionality (and it's a very clean and quick site as well) you've got one further great bonus. On hte more normal shopping comparison engines you only get shown (at least, in the first few pages of results) those people who have paid to be presented in those first few pages. Here, you get a real comparison of all of the different offers, making it much easier for you to find both what you want and the best deal on it.