Jump to the Most Recently Used Desktop Space with a Hidden Gesture in OS X Lion:
Enable:
defaults write com.apple.dock double-tap-jump-back -bool TRUE;killall Dock
Disable:
defaults delete com.apple.dock double-tap-jump-back;killall Dock
Show a Full Size Window Preview in Mission Control
Enable:
defaults write com.apple.dock expose-cluster-scale -float 1;killall Dock
Disable:
defaults delete com.apple.dock expose-cluster-scale;killall Dock