Textmate and vim. Textmate with the usual ruby and rails bundles (or whatever they're called), vim stock. To be honest, I only care that my editor does syntax highlighting and column editing, automatic indentation is nice if it's there, and there are 1-2 macros I use in textmate, but that's all.

Emacs with a bunch of custom configuration that I've shared on github. It's a bit outdated but the Ruby/Rails stuff hasn't changed much.

Eric Davis

Vim with some custom coloring and some buffer hacks.