Canon's new ZOOM fisheye lens sure looks to be promising. Zoom it out to 8mm and get a really cool circular image in the center of the frame with black, unexposed area on the outer areas of the frame. Zoom in to 15mm and it produces a normal fisheye view with straight lines turned into curvy ones.
It's the first "L" series fisheye lens, which means we get weather sealing and higher grade optics. These lenses also support rear gelatin filters but no protection is provided or available for the exposed front element.