For vi users, I recommend this plugin: https://github.com/mileszs/ack.vim. I like it better than simply replacing grep with ack. This has made me a lot more productive, as I can do complex searches MUCH faster!

Textmate users should absolutely check out AckMate (https://github.com/protocool/AckMate), which runs circles around "find in project".

Generally speaking, matching regexpes using perl instead of grep is often a win :

    perl -p -e 'm/regexp/' somefile