There are a number of places what I look for free utilities and programs. Some improve the windows experience and some are for other specific functions. The first three sites listed below review the software and the last one has lots of software but usually just has a description of what it does.
Hopefully someone else finds them helpful.

http://thefreewarejunkie.com/
http://www.freewaregenius.com/
http://elitefreeware.blogspot.com/
http://shellcity.net/