a lot... I make a lot of playlists. Some of them are a single band. Makes it easier for me to go right to my favorite band instead of scrolling through my music. Very rarely (if at all) I will ever scroll through my music collection. I just make playlists.
AC/DC
Birthday CDs (burnt CDs friends gave me for my 17th bday)
Black Label Society
Black Sabbath
Blues (my blues collection)
Bounce On (the music from the iPod/iPhone game Bounce On
Buckethead
Buddy Guy
Chicks (all the songs that are sung by women)
Chillaxin' Music
Classics (all my music from the 70s - 80s)
Cuhnool's Mixes (my GarageBand mixes)
DJ Ravine (this guy from YouTube. Makes groovy happy hardcore mixes)
Down n' Out (a friends band)
Flobots
Halo Soundtrack (all four Halo soundtracks)
Heavy (all my heavy music like death metal and screamo)
Indestructible ( one of Disturbed's great albums)
Jenkees (songs by Ronald Jenkees from YouTube)
Jim Gaffigan (Jim's Beyond the Pale album)
Joe Satriani
Judas Priest
Kenwood (my mix of music that I play on my stereo in the car for other people)
Lauren (my girlfriend's favorite songs)
Led Zeppelin
Mis-Teeq (a band from the game Midtown Madness Chicago Edition)
Now Playing (the top hits from 2008 and 2009. More to come)
Now That's What I Call Music! (all my Now CDs)
Queen
Rap (all the rap in my library. currently it is 95 songs)
Remix (Idk, just a bunch of songs I like)
RHCP (red hot chili peppers songs)
Run-DMC
Rush
Screenflow Play (music I play during screenflow recordings)
Shock Value (Timbalands album)
Slipknot
Supernova Records (a collection of local screamo bands)
THPS2 (songs from the Tony Hawk's Pro Skater game)
whew!