The 100 Second Film Festival is “a collection of short videos presented to an audience in person or through the medium of cable television or the Internet” with the only requirements being that the films are 100 seconds long and are released under a CC BY-NC-SA license. This allows the film festivals – the screenings are decentralized – to pool past submissions as well as new ones for their lineup. Whoever is curating a specific festival can put together the lineup in any fashion they see fit, although ideally, each screening will contain at least a few works produced by the local audience where the screening is held.

This year’s call for entries was just announced, with the deadline to submit a short extended to Dec 15th, 2008. From 100SFF:

The 100 Second Film Festival is an unique yet accessible universal collaboration. Launched in 2005, this evolving anthology of videos embraces the raw creativity from producers of all skill levels and backgrounds, encouraging them to submit their best work. Works from all genres are welcome
adhering to the common constraint of 100 seconds or less in duration.