textmate.el is decent. https://github.com/defunkt/textmate.el

I just setup anything mode yesterday (textmate.el's find in project was too slow) with a gist I found that searches the current git repo:

https://github.com/zpinter/emacs.d/blob/master/anything/init...

http://trickeries.com/archive/find-file-in-git-repo-with-ema... installable via marmalade

find-grep-dired is fantastic and fast. Granted it works off of a directory as opposed to a project.

I use full-ack: http://nschum.de/src/emacs/full-ack/ (which uses ack: http://betterthangrep.com/ underneath)

I have it bound to C-c a and it works great. Finds all references in a multi-hundred thousand line C/C++ code base in a few seconds.