Lego toys may be small, but they can pack a hell of a punch.
Something I hate about most action movies I see is that the actual fight sequences are nearly incomprehensible due to quick-cuts and confusing camera angles. Case in point: By and large, I enjoyed The A-Team, but there were a couple of moments where I had no idea who was doing what in a fight. Anyone who's considering making an action movie should watch this video. Not only is it one of the best shootout scenes I've ever watched, but it was made with Lego toys!
This is the latest YouTube video by Custard Productions, which has put together a number of amazing stop-animation videos featuring Lego characters and settings (the Metal Gear Solid parody is especially brilliant).
In terms of quality, I'd put this up with the shootout from Heat. Not only does it present an exciting, coherent narrative from a single angle, but it also features a sequence where a dude flies with a jetpack.
I'm not sure how long it would take, but I'd love to see a Lego adaptation of the lobby sequence in The Matrix. Based on Custard's track record, it would probably look amazing.