I can't wait for my 50 to show up.
Calder...I rented the Tokina fish from Borrowlenses. I'm a rookie, but I thought that it was a great lens and I had alot of fun with it. I suggest that you rent a few to try them out and see which have an effect that you like on the D40X size sensor.
A couple shots from the Tonina 10-17 fish on the D40X...not great pics but they demo the fish effect at each end.