Director Sandy Collora wanted to make a short film that would help him get noticed by the film industry. So he made an 8-minute film called Batman: Dead End, in which Batman fights the Joker and two other movie villains. You can read a review of the film here, and download Batman: Dead End here.
Some filmmakers in the Philippines have also made their own Batman movie. Their version is "an outlandish so-bad-it's-good production" that includes several musical numbers. Here's a review of Alyas Batman and Robin from Film Threat.com.