Valve have created Expiration Date, a 15 minute animated short featuring all the Team Fortress characters.
Portal: Survive! is a live-action short film based on the Portal game, and its tie-in comic Portal 2: Lab Rat.
When Gordon Met Chell
Portal joins forces with Half-Life in this short film called When Gordon Met Chell.
Half-Life Black Mesa
A relentless team of fans have finally released Black Mesa a remake/upgrade of the first Half-Life game from Valve.