for me Tasker, Astrid todo go launcher is a must
with this combined with an app called secure settings i can do the following things
1 when i am at home my screen is turned on by a swipe, at work i have to use pattern unlock to unlock the phone, in my car its just a swipe to use the phone.
2 when i enter my car the phone goes into car mode different ringtone etc, when i exit the car i end up with a time stamp telling me what time i left, it also remembers where my car is parked this is for parking meters and to relocate my car later on by pushing a simple button
3 when i get home tasker turns off my data, changes my ringtone and turns off the bluetooth
4 when at work my ringtone is the start to "seether remedy" as its a noisy place
this is probably the best to do out there, it has also a web based unit and syncy with your google account, you can include others in your todo via email and it works in with tasker as an example if i am at work astrid knows this via tasker and will remind me i need to take my tools home, or if i go to the supermarket it reminds me to get beer!!
3 GO LAUNCHER
this is a better launcher which also comes with a very cool new wallpaper skin
if you want to know how to to this just ask