Cool iPhone/touch Apps, what do you like?

Ambiance, for those with trouble sleeping like me. Countless "white noise" type options to mix and match, plus fade out options for the sleep noise gnerator, and fade in options for your alarm sound. I currently use my own rainstorm, windstorm, train on the tracks noise to fall asleep to, and we wake to a Chinese gong that slowly increases in volume over 45 minutes so we don't get jarred awake. Well worth the 99 cents it costs