The Nikon 1 system is very under-rated. Check out Andy over at the WordPress blog NikonAndyE - he's got an amazing array of lenses, and every Nikon "D" body ever made. He's done some interesting stuff with the V1/J1 and come away impressed.
That would give you something really portable with the ability to use your standard Nikon lenses with a 2.7x crop. (one photo Andy posted on another forum was the V1 with the FT1 adapter, a 1200mm lens and the 2.0x TC - lol