Nikon D700
I bought this body on a whim, not because I really needed it, but because it was really inexpensive. Like really. I paid the equivalent of US$ 825.- for it used, having found it in a local classified ad list. It was inexpensive because the original owner had managed to get the glass in front of the sensor scratched when cleaning it, but the images have no traces of any scratches at all. This is my first full frame digital SLR, and I'm looking forward to seeing what that can do when equipped with a bright prime. I know the camera already and know that it's a real performer, not least at high ISOs. It shares batteries and grip with my D300s, so I'm all set with accessories.
I bought this because it simply yelled "buy me!". The price was very good. It's a really excellent body, which I had shot with before (a friend used to have it), and it was a way to get a full frame body in an approachable way.