Shatner's the man - I know of no other actor of his stature and success who pokes fun at himself with so much gusto!
Here's a (weird? strange? fun?) clip of William Shatner in the 1998 movie Free Enterprise [wiki], where he played himself staging a rap-version of Shakespeare's Julius Caesar in hopes of finally being taken seriously as an artist.
("Free Enterprise" is out on 2-disk DVD now.)
I can also say (and this is a great story) that a relationship I was in for two years began with "No Tears for Caesar."
-Nathan