Good find. I am a music addict and rarely leave the house without the ipod with around 1,400 songs - that way I've got a little of everything. My separate hard drive for the PC has ~ 13,000 tracks on it.

Groups/Artists that I can think of; how about a top 10 that I ALWAYS have with me:
1. The Beatles
2. Dave Matthews Band (going to see them in Motown in August, anybody else going?)
3. Marvin Gaye
4. Otis Redding
5. Rolling Stones
6. Paul McCartney (solo stuff or with Wings)
7. John Lennon (solo stuff)
8. Led Zeppelin
9. Van Morrison
10. Simon and Garfunkel

and many, many more.