[Koenigseggfire]

This could be a favorite band type thing, but just list the bands you play as the control for sound-checking and comparing your gear. 
For me:
Kamelot; great variety of sounds.
Hopsin; test for hip-hop stuff
Insomnium; lots of high notes for a metal band
The music for Arby n' the Chief season 6; Just some simple techno.
 
Also, what are you favorite EQ settings? Mine are classical and electronic.

 

[Kiont]

Tool, Pink Floyd, Dream Theater

Mostly because I listened to certain songs so many times that it's easy to notice any changes with different gear.

 

[Romis]

Although there is a special test disc for headphones (from Head-Fi) and also several different "special" discs, I use my favourite label ECM because that kind of music I listen to mostly.

 

[vertical]

Tool, Pink Floyd, Dream Theater

Mostly because I listened to certain songs so many times that it's easy to notice any changes with different gear.

Yep, I tend to use songs that I've listened to a lot as well.
Floyd - dsotm
Kaempfert - happy trumpet
Some well recorded female vocals
Sabbath - war pigs

 

[whirlwind]

For me, it would be my favorite bands.
 
Tom Petty & The Heartbreakers
 
AC/DC
 
Pink Floyd

 

[vertical]

Interesting that Floyd is common to many poster's equipment evaluation list...

 

[Seekky]

Animals As Leaders 
Asian Kung-Fu Generation
Blackmill
Daftpunk 

 

[thatBeatsguy]

Daft Punk - EDM
Black Eyed Peas - EDM again
Michael Jackson - lots of detail, great for testing (or just downright dancing, lol)
Queen - Bohemian Rhapsody fits in with a lot of genres, so great for a quick all-round tester
Yiruma - Solo Piano
Issac Shepard - Also Solo Piano