I have a D300 that is my main camera (Weddings and events), a D90 and my old D70 for backups.
Bought my wife a D60 and after a week, took it back and bought another D300. In my mind no comparison between consumer cameras and the PROsumer cameras. Just the weight difference tells a lot about the camera, let alone the features. The D300 will outlast the D60. Like SYnthetic mentions, the D40/D60 are smaller bodies and I have big hands. When I was shooting film, I was using Nikon F5's with motor drives. THOSE are heavy!. Just feel a better balance with the larger bodies.,
Oh my gosh I love the d60! A friend I have recently bought two of them to make a 3d rig. He's a little weird. (And foreign) He made some kind of rig using two should rigs from http://www.habbycam.com I haven't seen the actual rig yet but I have seen the 3d footage and it actually looks legit!!!