I found this one over on Alton Brown's blog about a year ago. I believe this commercial won Honda a design achievement award. When I first saw this I thought some parts of it were 3D animated but in fact, it was just an incredibly elaborate reaction with an incredibly high budget for filming. The budget takes away some of the fun of a rube goldberg machine but you still cannot deny the charm in this video.
This one was commissioned for two Swiss artists Peter Fischli & David Weiss, the actual chain reaction goes on for about thirty minutes but as you can see from the four minute sample on the internet, its some pretty elaborate stuff and I remember hearing that they went under a fair bit of scrutiny from the person who commissioned it up until the actual device was done.