There're plenty of super-wideangle zooms that're popular. Sticking to DX format, the widest without going fisheye are the new Nikon 10-24mm f/3.5-4.5 and Sigma 10-20mm f/4-5.6 or f/3.5. There's the Tokina 11-16mm f/2.8 which is fast for the money but seems to be plagued with quality assurance issues, or there're 12-24mm lenses from Nikon, Sigma and Tokina (the Sigma also works on FX format), and Tamron have an 11-18mm. Not sure if I've missed any out...probably. There're also various primes.
I've got a Nikon-fit Sigma 10-20mm f/4-5.6 on the MM now.
edit: excuse poorly arranged post...you have lots of choice.