Mega Man: The Movie. Its got a level of polish we're not accustomed to seeing from most fan films -- by which we mean we can watch the entire thing without involuntarily cringing our faces off.
The full movie is hosted for free over at ScrewAttack. All kidding aside, it's totally worth watching. You can really tell that a lot of hard work and love for the franchise went into the making of the film. Also, a lot of mustache pomade.