ack is a grep-like program with optimizations for searching through large
trees of source code.

Key improvements include:

    * Defaults to only searching program source code
    * Defaults to recursively searching directories
    * Ignores blib directories.
    * Ignores source code control directories, like CVS, .svn and _darcs.
    * Uses Perl regular expressions
    * Highlights matched text

WWW: http://beyondgrep.com/