If you're having trouble finding a gift for someone, GiftMating can help you narrow down the list. The web service uses Amazon's recommendations database to help you choose something appropriate.
To use GiftMating, just find two things they like — maybe it's two books, two CDs, a book and a movie or something to that effect — and GiftMating will find other items recommended to fans of the first two. It's easier than rooting around on Amazon for gift ideas, and it actually produces some pretty good results, or at least starting points. Hit the link to try it out.