QuoEdit

Well, for one thing, it will work on Jaguar. My computer lab at school is dragging feet to put Panther (let alone Tiger) on these machines. All of the great text editors (Text Wrangler, SubEthaEdit) are for Panther only.

Assuming you mean TextEdit, from the list at the top of the page: Supports AppleScript powerfully; fully Scriptable, Recordable with/without the Script Editor and Attachable. Some menus are customizable and up to three menus can be added. Supports regular expression search as well as multi-file search. What's the advantage of this over SubEthaEdit or Smultron, now that's a good question.