Mac OS X supports a decent batch of emacs-style keybindings -- C-a and C-e work, C-k and C-y work, the cursor-movement keys work. Give me C-s and C-r and I would be even happier, though. Or C-x C-w to write half-written drafts of news.yc posts to files for backup. Or C-x C-i to import text from files on disk. The list goes on and on.
I type an unfortunate amount of text into browser fields during the course of a day. It would be nice to be able to make these fields work more like a decent editor, and by that I don't mean TinyMCE.