There's also the Zeiss 30mm fisheye which is no longer in production I think but turns up occasionally on ebay.
Don't forget the new lenses which are due out in the future: Flektogon 2,8/35mm, Flektogon 2,8/50mm, Biometar 4/150mm, Biometar 2,8/150mm, and a Vario-Biometar 60-140mm