which is a nifty browser for Squeak.
Part of what I like about it is the way it integrates with changesets to let me click my way back through revisions in the editor. So I'm less fearful of making changes because its so easy to revert. It also lets you put lots of little method editors in panes in the window making it easy to reference code from somewhere else while editing your method.
I could maybe even give up vi for it. :-)