Portal: Survive! is a live-action short film based on the Portal game, and its tie-in comic Portal 2: Lab Rat.
Portal: Terminal Velocity
See what three guys can do with a portal gun in this funny and clever short film, Portal: Terminal Velocity.
Valve have created Expiration Date, a 15 minute animated short featuring all the Team Fortress characters.
Valve's Source Filmmaker
Valve have announced the Source Filmmaker, their tool for creating animated films in a very intuitive way.