therse too many i can think of, my favorite is Don Hertzfeldt's Rejected, 'I am a BANANA.' classic.
this is a good one for the forums
http://www.compfused.com/directlink/851/
im kinda keen to compfused
http://www.compfused.com/directlink/302/
yet more
http://www.compfused.com/directlink/302/
and last
http://www.compfused.com/directlink/302/