A small but important tip.
In Mountain Lion, when you hold down a key, an iOS-like accent popup will appear.
This feature is really annoying if you, like me navigate files in Sublime Text 2 running vintage mode. What I want is the key to repeat the letter, and luckily there's an easy fix for that.
To disable the pop-up simple run this command in your terminal:
$ defaults write -g ApplePressAndHoldEnabled -bool false