Yup, TextWrangler is great. Quite sophisticated for a free app, regex support and all. I like the "find all" interface.
Only marginally related, but for batch file renaming, i like File List (
http://www.manytricks.com/filelist/). My only gripe with it is that it’s a "rogue" window without a dock icon, but apart from that, it’s very easy to use.
Oh, and I use Coda too. Has a few nagging limitations, but fantastic editor overall.