I'm currently selling my D80. In an unusual turn of events, I decided to downgrade to the D40. It's 6 megapixels instead of 10, but I'm very happy with my decision. See here for some quick test results at my nephew's birthday party. Not that there was anything wrong with the D80, but the extra advantages it offered over the D40 didn't tip the balance in its favor, especially when considering the fact that I can walk away from the deal several hundred dollars in the black.
The extra resolution isn't a concern to me at all. I got pretty good results from my D70, and it was *only* 6MP. The smaller size is great on the D40. The only thing that really bugs me about it is that it doesn't autofocus with my 50mm 1.8. That being said, I'll probably eventually get the Sigma 30mm 1.4, which *will* autofocus, opens to a larger aperture, and has a more useful focal length.