What are the good ones? Car and non-car specific.

For my iphone I couldn't live without
Tripit - best travel app ever. Forward your booking confirmation emails for flights, hotels, car rental and it builds an itinerary for you.
Bmwhat - car fault reading and coding from your phone
Dropbox - best camera backup
Sky+ - remote record from anywhere
SoundHound - identify that song

What apps can you not live without?