Female vocal:
Diana Krall "Live in Paris"
Amanda McBroom "Dreaming"
Robin Holcomb (self-titled)
Joni Mitchell "Song to a Seagull"

Male Vocal:
Frank Sinatra "Nice 'n Easy"
Lyle Lovett "Joshua Judges Ruth"
David Sylvian "Secrets of the Beehive"

Jazz Ensemble:
John Coltrane "Blue Trane"

Classical:
Vivaldi "Four Seasons"
(Boston Symph./Seiji Ozawa/Telarc)

Orchestra with Chorus:
Orff "Carmina Burana"
(Atlanta Symph./Chorus/Robert Shaw/Telarc)

Solo Instrument (Organ):
Bach: Toccata and Fugue in D minor
(Michael Murray/Telarc)

Solo Instrument (Piano):
Beethoven Op. 111
(Ivo Pogorelich/Deutsche Grammophon)

Honorable Mention (just for the sheer power at the end):
Telarc "1812 Overture" (if your system can at least reasonably reproduce the cannon shots and survive, it can survive anything)

Movie DVD or Soundtrack:
"Glory"
"Gladiator"
"The Matrix"

Rock/Alternative:
Nine Inch Nails "Downward Spiral"
Marilyn Manson "Mechanical Animals"
Rammstein "Reise, Reise"

I make it a point to take all of these if of when I audition any piece of audio equipment. I never listen to anything the salesman might hand me.