I am a full time student and part time DJ. I use iTunes to do all my DJ/Music related things and iMovie/Final Cut Pro HD to edit numerous videos for my TV Production class in school. Other then that, the usuall (Safari, Word, iPhoto, iDVD, iChat, Mail, etc.)
Made the switch about six months ago; I already own an iMac G5, a Mac mini, and soon a 12" Powerbook. I'll never go back, and I've already convinced a few people to buy macs of their own! (They want me to work for Apple as a sales rep).