How about this for a business idea that captures users’ intent and therefore enables highly targeted advertising? A web application that allows a user to broadcast a brief RFI (Request For Information) to all or selected companies in one or more categories, as well as to their customers. Besides advertising, additional revenue would come from premium services to companies, e.g. being featured in their category.

So for example, I recently needed to know which Wiki software platforms included a specific feature that I wanted and had to post the question to a number of forums, Q&A sites and individual Wiki software providers to find out. With RFIblast, I could simply have posted the question, selected a number of Wiki software providers and had them - or their existing customers - respond. RFIblast would have known that I was looking for a Wiki product and served me relevant ads.

The service could serve as a lead generation tool for businesses and a product research tool for potential buyers. 

To prevent spamming, all responses would need to be in-site and standard anti-spam measures would be needed e.g. captchas and user-moderation. Also, member companies could be given a choice as to whether they want to receive questions by email or just subscribe to an RSS feed.

To prevent silly questions (and answers), a rating system would be required and companies could opt to only receive questions (from members) that have not been rated down.