While Bing is the big deal, another decision engine has quietly been made available for all to play with and help make stronger. HUNCH, from a team lead by Caterian Flake of Flikr fame, has been in invitation-only Beta since March but it was opened up to the general public this week. The concept is simple and fun. You simply choose an existing topic, or recommend a new one, and then the engine asks you a series of qualifying questions (5 in total) and at the end of the questions you will be provides with the top 3 choices based on your answers along with a wild card choice.
For example, I clicked on the 'What kind of sunglasses should I buy?' thread and was asked what my price range was, what my gender was, if I was looking for sporty or fashionable, what kind of frames and lenses I preferred and what size lenses I felt fit my face best. I was then given my top 3 based on my answers and a wild card choice. And one of the top 3 was a pair I was considering buying before I even found Hunch.
Since you have to create a username and password account (free) as you answer more questions Hunch gets to know you better. Also, the overall Hunch engine increases its knowledge base as more people use it. The whole site is monetized in that if you click on one of the choices you will be taken to a site that either sells the choice or is a company that sells it so you can contact them.
Go check it out, play with it, and then come back and give your opinion of what the SEO challenges would be for Hunch.