You've come a long way, baby. Back on your birthday on January 9, 2001 at Macworld Expo, you were just a music player and manager -- the Apple-ized offspring of SoundJam MP, given a fresh face. Soon enough, though, you would become the conduit for iPod synchronization, the platform for music and video purchases, and now the landing zone for the iOS App Store.
Not bad for a ten-year-old. Even though we may tease you for your vanities and complain about your sluggish, do-everything approach, we still couldn't do without you. Happy 10th birthday, iTunes!
Commenter Kevlar points to our rundown of the iTunes user interface from 1.0 to 7.0, here, and Twitter buddy MightyKenny points to a YouTube clip of the actual 2001 introduction; it's embedded in the second half of this post.