Nikon speedlight flash would be nifty...
A sexy model would be nice too...
You do not mention any lenses, but Nikon has some pretty spiffy lenses that would make life pretty fun. The new 70-200mm f/4 VR-G seems like a sweet lens.
The new 85mm f/1.8 AF-S G is perhaps *the* sharpest, best-resolving non-macro prime or zoom lens in the current Nikon lineup, and it is light, small, and fairly unobtrusive, and has such AMAZING shaprness that it allows pretty good cropping-in with plenty of sharpness--especially on a high-0desnisty, high-megapixel count sensor like the 24-MP one in your D7100. The new DxO Mark tests of 72 lenses on the Nikon D600 and D800 (same,exact lens samples, same models of course) show that the 85mm 1.4 and 1.8 G are basically, the *best* lenses on those 24- and 36-MP cameras, followed closely by the new Sigma 35mm f/1.4 AF lens, which is in third place, and FAR above many other lenses costing twice as much.
For the money spent, the 85mm f/1.8 G-series Nikkor is an AMAZING value. I am enjoying mine more and more.
Now that we have 24-MP cameras and an affordable, amazing lens like the 85/1.8-G, it's possible to shoot "loose", then crop-in later, and get amazing shots.