Once

This movie is incredible. Not only is the story wonderful (about a girl and a guy, named "Girl" and "Guy" in the credits, who meet over their love for music and a Hoover vacuum cleaner-- heartwarming and touching to the max), but the film was made for only $160,000. It then got picked up by Fox Searchlight Pictures and made it to the big time, doing well in U.S. theaters and winning awards left and right. Every filmmakers dream. 

More fun facts:

The movie's two main characters are played not by actors, but by professional musicians-- Irish rock band star Glen Hansard and Markéta Irglová. 

Once also, and perhaps most notably, won an 2008 Academy Award for Best Original Song for "Falling Slowly," which the duo wrote and recorded for the movie. The movie's soundtrack as a whole was also nominate for a Grammy. 

The film was shot in 17 days. Dealing with such a small budget, the film crew often filmed the crowded streets of Dublin without permits from the city or permission from the public. This they accomplished by using long lenses and filming from a distance. 

The crew also saved money by using mostly natural lighting and filming in their own, or friends, apartments.