Hand break is alright so I have heard, I have it downloaded and want to use on some stuff... it looks like it is for windows, OSX and Linux too. They recently changed their name (and product), can't remember the name but the product is now called MediaFork, I have heard only good stuff about it.
Now for OSX there is ffmpegx, I am using it right now to convert to H.264 (VERY nice compact compression). However ffmpegx is picky in how it converts video.