ack is the replacement I wrote for grep, aimed at large trees of heterogeneous code.
Using it will change your life, but why? Here's my top 10 list:
Note that ack's --perl also checks the shebang lines of files without suffixes, which the find command will not.
To install it, install the Perl module App::Ack. Your coding life will never be the same.
Visit the home page at http://petdance.com/ack