Here's who I'ved signed up so far:

KiK......................... Flavor Flav
Sean........................ Zach Braff
lemonbrickcombo............. Samuel L Jackson
Mirri....................... Renee Zellweger
vikram...................... John Turturro
Galactic Frank.............. Nick Frost
wrightylew.................. Hayden Christensen
yes_........................ Ewan McGregor
Saint Cronin................ Tim Westwood
Mr John D Traynor........... Mr Mark E Smith
Bamos....................... Jack Black
Bamnan...................... David Schwimmer
Alex-in-Ciderland........... Ricky Gervais
Brainlove................... Dustin Hoffman
jimitheexploder............. Grandmaster Flash
wishpig..................... Julia Stiles
Pocketmouse................. Ellen Page
Mike Diver.................. Lemmy
douchebag................... Dan Aykroyd
dukebox..................... Rick Moranis
DanielKelly................. Dave Mitchell
Stealthy.................... stunt ninja, voiced by Frank Bruno
Brian May................... as himself