@Aleks: I've got a Tokina 12-24mm that I like a lot. The Nikon was just too much money, especially when I was living in the US. While the 10mm would have been nice, it just wasn't going to happen. I paid around half the cost of the Nikon for the Tokina. There was a website with some good review information that ended my indecision.
A couple of samples of what is coming out of it (click to go find bigger versions):
For white balance, I sometimes use the sampling method and sometimes auto, unless I'm finding it off in which case I'll change to cloudy as it does a bit better job in some seemingly sunny conditions.