Locale - this app is very cool. I have a profile for work, home, my parent's house and a default setting for when none of those are active. Oh and I have one for night time. I get to work and it turns the volume down a bit, changes my 'desktop' image, turns of the wi-fi (so the security guys don't bug out), and it changes my ringtone and volume. At home the Wifi goes on, pictures changes, volume goes up etc. At night I have it turn of all network stuff besides the phone istelf and mutes the sound. It's great. Love it!
I use the Weather Channel and Shop Savvy apps quite a bit too