If you have the initial cash (and room) to get a pinball machine, I highly recommend one. Because they're collector items now, they basically don't really depreciate (unless you buy a brand new one). In fact, for the past 6 years (until the economy went to crap) they had been appreciating in value. So basically you put $1k to $2k into one, play it for a year, then trade it for another one, no money lost. And if you ever need the money, just sell it and you'll have your money right back. Unlike Golden Tee's, pool tables, etc which basically go towards zero the older they get.
Right now I have a Stargate, Star Trek: The next generation, Jurassic Park, and Tommy the pinball wizard. They're a good change of pace from the 360. I would like to get a Spiderman someday, but I'd have to sell one of the above first (which would be very difficult to do since I love all of them).