I use emacs in a terminal window for probably 75% of my editing, and textmate for the other 25- I have Aquamacs but couldn't get into the flow with it for some reason. I keep all the default keys for ctrl/etc, and it does help a bit that they newest macs have changed the enter key that used to be to the right of spacebar to alt.

While it's not really emacs, I generally do most of my development in Eclipse- but I change the keybindings to Emacs mode (window\preferences\general\keys). Makes eclipse almost nice to use.