I got a brand new sigma 15-30mm on Ebay – I guess this lens has been discontinued and is going very cheap at the moment ($250). It doesn’t make a real superwide on the d70 (although it is significantly wider than the kit 18-70), but put it on a film camera and it is crazy wide:
That’s not the best shot but the others on my first film rolls don’t show how wide it is as clearly: http://flickr.com/photos/awrose/tags/1530mm/
Anyone looking for something cheap that’s a bit wider than the Nikon kit lens (I didn’t check and see if it’s available for Canon, etc) might want to take a look for one, although it is rather enormous (but not all that heavy).