TextWrangler

From Bare Bones Software, makers of the legendary BBEdit, comes TextWrangler.

This award-winning application presents a clean, intelligent interface to a rich set of features for high performance text and code editing, searching, and transformation.

TextWrangler's best-of-class features include "grep" (regular-expression) pattern matching, search and replace across multiple files, function navigation and syntax coloring for numerous source code languages, code folding, FTP and SFTP open and save, AppleScript, Mac OS X Unix scripting support, and much more.