To give myself a bit of a break from the white seamless, I've done a couple of shoots in the house with the SB-600's. Both of these sets were shot in TTL mode, on stands, with white shoot-through umbrellas.
It was fun moving around the speedlights to get the look I was after. In the first shoot (on the left), I was attempting to emulate morning window light from the left. I'm happy with the result. In the later shoot (on the right), I tried several different shutter speeds. In the end, I went with a slower shutter to blow out the windows in the background. You can still tell it's a window, but you don't see any of the distracting shapes outside. I also adjusted the depth of field, to blur the background while maintaining a hint of the furniture.
Still wrapping my head around the ability to adjust both shutter speed and aperture to whatever I want, and then relying on the TTL speedlights to expose the subject properly. (Adding +/- to the speedlights to fine tune their exposure, of course.)
My system did tend to underexpose my subjects slightly. I have to remember to watch the histograms and adjust as necessary.