is an interesting topic related to web-enabled E-commerce and intelligent agents.
The concept is to see what others that share your taste
so that you can keep up with new examples.
A good example in action was MovieCritic.com, now defunct.
It would find other movies you were likely to enjoy
after you specified which others you had liked already.
Other information I've gathered so far includes:
Working filtering examples (some dead links included!)
Search for more articles on "Collaborative Filtering" and "intelligent agents" at About.com
Last updated: February 12, 2002