These guys just totally blow my mind. I recently saw their show at MOMA. It was around the time I started making miniatures for Light Boxes [The Movie], and I felt a surge of inspiration as I marveled at the miniature sets they had created. There is a dark sense of fantasy in their films, with touches of esoteric influences. Their work is not limited to stop motion though... so while I was amazed to see an up close look at the doll parts used to construct figures and so on, I also was taken with their stage sets, beautiful book cover designs, illustrations and hand done typography. Though they are first and foremost fine artists, as they grew in popularity they made several commercials and also worked on Peter Gabriel's "Sledgehammer", though they did not direct it, and apparently were not pleased with the final video. Another thing to note is that these guys are the coolest looking identical twins I've ever seen.
It's so hard to pick one video, but above is their best known work, Street of Crocodiles, based on the short novel of the same name by the Polish author and artist Bruno Schulz. I also reccommend The Calligrapher.