I like the FFXII commercials with Patrick Stewart's voice-over, since Patrick Stewart is God and adds class and credibility to everything he voices.

This ad for Syphon Filter 2 is oddly amusing, too.

:edit: Also, I love those Ratchet and Clank commercials that feature 'real-life' demonstrations of the game's weapons. I've never played them, but the ads are clever and funny.