I'm spending all of mine ($500) on home furnishings and improvements. So far, I've bought a couch, tile caulk, decorative rope, wood putty, spackle, staining pads, and wood stain. I'm going to build a media center (we have most of the supplies for this), paint the bathroom, install new shelving, etc. I think it'll be a lot of bang for my buck.
We'll save 80% of my fiance's and use the other 20% for the inevitable project overruns. ;)