I recently had the chance to play with a Canon 400mm f/2.8 L lens, courtesy of Chris. It's a behemoth with about an acre of glass at the front!
This shot isn't from that lens though, this is shot with a "home brew" 400mm - my 200mm with an old store brand 2x converter. Obviously the images from this combination can't compete with the sheer gorgeosity of the 400mm prime but I think it does ok, this image is pretty much straight out of the camera.
Link of the day
Lyrical This. Lyrical That