Greetings -- when looking around to assemble a transcribing system for Mac, I've found a very cool solution at O'Reilly's Digital Media, by David Battino:
http://digitalmedia.oreilly.com/2005/03/09/transcriber.html
It consists of AppleScripts for Tex-Edit Plus, a speech-capable editor also supporting AppleScript. The scripts to rewind and replay are provided in the article, names ending in function keys like _F10 -- that's how Tex-Edit assigns keys to them.
What does it take to adapt them to TextMate -- where's I put them, etc.?
Cheers, Alexy