Studio 4C, The Japanese animation studio whose work first came to my attention on The Second Renaisance (parts 1 & 2) on the Animatrix compilation.
Tekkon Kinkreet was the next release that I heard critical acclaim for. The character designs have stepped away from the normal anime style. The clips below shows the dynamic blend of CG and traditional 2d animation to produce a distinctive, energetic storytelling style...
I found The above trailer up at TwitchFilm which has become a favourite site for info on anything weird and/or wonderful in Film and Animation from around the Globe. The media player has hundreds of classic and bizarre trailers.