Had a hard time not including DVD-A's.

Queen - A Night At The Opera, always pull this one out when someone comes over to hear my system for the first time.

Allman Brothers Band - Hittin The Note , Just when I had about given up on these guys, they come out with something like this.

Renaissance - Prologue on any one of a half dozen CD's. When Annie starts to sing people usually sit down and listen.

As for live recordings

Porcupine Tree - Coma Divine , You guys who have seen them live are so lucky