I never made it to a Keanu Reaves Dogstar show. But I did see:
River and Rain Phoenix playing in their band Aleka's Attic in 198?.
Milla Jovavich playing the 15 Minute Club in DC in 1994
Jason Schwartzman playing drums in Phantom Planet at the Black Cat
Kevin Bacon in the Bacon Brothers at Camden Yards as we exited
Zooey Deschanel pretending to be a singer while M Ward played guitar (or is she a singer pretending to be an actor who plays herself in all her roles?)
Surely you must have some cheezy ones to share?