"Alice," an electronic piece of music of which 90% is composed using sounds recorded from the Disney film 'Alice In Wonderland'. Phenomenal remix skills on display here. 

Considered by some to be THE original user generated content, here is 1977's "Hardware Wars."  The movie, starring Fluke Starbucker and Ham Salad apparently took $8000 to make, though distribution was understandably more difficult at the time.