I might finish up with furnishing my apartment. I've been here about 6 months now and I'm only half done. I've got everything I NEED to get by, but I still need various end/coffee tables, probably a recliner, some lamps, wall hangings, a bookshelf, couple pieces of bedroom furniture, and some kitchen odds and ends.
Or I might buy a big fat TV, since I don't have one and currently use my monitor for TV watching. Though I seriously doubt I'd spend the whole 5 grand on a TV, maybe half of it.
Or I'd use it as a down payment for a new car, since my current one is getting a bit old and I'll be in the market for one soon anyway.
edit: I've thought I'd like a pair of HD650s, ZU cable, RSA raptor, and a nice source. But I really have several better ways to spend that money these days.