I love TextMate on the Mac. Personally I think it's the best thing since sliced bread :)

The only problem is that it's not cross platform and it's not available when you're connecting over SSH into a server to fix some problems. I use Vi most of the time to just edit configuration files, etc, but I found it lacks the power I need for doing serious hacking (for all the vi lovers out there, I'm willing to admit this is due to my ignorance).

I'm re-trying to learn Emacs to do some Erlang hacking but I've always been turned off the by the relatively cryptic key combinations.