For me, it's gotta be Digible Planets. That was THEE band right before I went into Islam and stopped listening to music for years. Every time I hear them, I remember the days before I knew about Islam at all, happy, peaceful...just going to shows and riding my skateboard. I always get taken back when I hear them...
http://www.youtube.com/watch?v=dJKIPz1c0Gw