Classical
Beethoven (all 9 symphonies)
Bach (large selection, most of the brandenburg concertos)
Mozart (large selection)
Handel Messiah
Rimsky Korsakov Scherezade
Brahms piano concertos
Mahler (symphonies 1,3,5)
Pop
Eva Cassidy (everything)
Bonnie Raitt (everything)
Billy Joel
Carol King
Cat Stevens
Dr. John (lots-- huge fan)
Jackson Browne (lots)
James Taylor
Jimmy Buffett
Paul Simon
J.J. Cale
Jewel
Joe Cocker
Sheryl Crow
Classic Rock
AC/DC (lots)
The Band (entire soundtrack from the Last Waltz, Songs from Big Pink, etc.)
Led Zepplin (lots)
Hendrix (lots)
Mountain
Government Mule (huge Leslie West fan)
Janis Joplin
Blind Faith
Jethro Tull
Bob Seeger
Grateful Dead
Beatles (usual stuff)
Allman Brothers
Clapton (Yardbirds, Cream, D&D, later stuff)
Fleetwood Mac
Rolling Stones (lots)
Chucky Berry (just about everything)
Little Feat
Lynrd Skynyrd
Neil Young (includes Crazy Horse)
Crosby Stills Nash & Young
Police
Steely Dan
Rod Stewart
Van Morrison
Santana
Steppenwolf
The Who
Pink Floyd
Queen
Tom Petty
Soul/Motown
Aretha
Wilson Pickett
Sam & Dave
Temptations
Martha Reeves
Eddie Floyd
Carla Thomas
Shirelles
Four Tops
Marvelettes
Marvin Gaye
Gladys Knight
Patti LaBelle
Later Rock
Def Leppard
Counting Crows (lots)
Metallica
Spin Doctors
Huey Lewis
Goo Goo Dolls
Red Hot Chili Peppers
Tool
9 Inch Nails
Radiohead
In Flames
Rage Against the Machine
Audioslave
Dennis Brennan (local Boston rocker)
Folk/Country
Bob Dylan (lots)
Dixie Chicks
Waylon $ Willie (lots- big Outlaws fan)
Arlo Guthrie
Flying Burrito Brothers (big fan)
Byrds
Poco
John Prine
Nancy Griffith
EmmyLou Harris
Johnny Cash
Taj Mahal
The Morgans (local CT band)
Reggae
Peter Tosh (huge fan)
Bob Marley
Jimmy Cliff
Toots & the Maytalls
Melodians
Comedy
Adam Sandler
Carl Reiner & Mel Brooks (full 2000 year-old man collection)
Lewis Black (lots)
Rob White
Woody Allen (all the early albums)
Robin Williams
Tom Lehrer (everything)
Sarah Silverman
Rita Rudner
Richard Pryor
Eddie Muphy
...Plus lots of other stuff.