The Joker's speech from Batman The Killing Joke, performed by Legos

Biggest surprise for me was to find out that this was not Mark Hamill's voice.  Great impersonation though. 

For those who don't know, The Killing Joke was a graphic novel written by Alan Moore in 1988.  It's probably the best Joker story around, and is definitely one of the better Batman graphic novels.  It was also important because it actually did affect regular continuity in the crippling of Batgirl, Barbara Gordon, which eventually led her to become Oracle.