I recently watched X-Men First Class and the Wolverine cameo was just so awesome! Gave me an idea for this thread
List your favorite cameos.
Some that come to mind for me are:
Bill Murray as himself (Zombieland)
Hugh Jackman as Wolverine (X-Men First Class)
Tom Cruise as Les Grossman (Tropic Thunder)
I'm sure there are a lot of memorable ones!