More generally, Ack is great for doing "recursive grep's" on source code. By default it does a pretty good job of only listing matches from filetypes you're likely to care about.
Wow I just learned about Ack as a result of your comment. This is a scale of magnitude better than grep -R [pattern] [directory] for searching through large codebases
Thanks!
Don't forget RAK, the ruby gem (works the same). gem install rak.
I've been using both RAK and ack for the past two days, and for some reason RAK misses things that ack catches. Probably a Cygwin issue.