Unreal Tournament 2004. I just bought it recently. The amount of servers actually playing is much smaller than I thought it would be, and the game itself is just a mindless frag/spam fest. I would be even more disappointed if I paid more than $15 for it.
Also, my PS3. While it does an awesome job playing/upscaling PS2 games, it so is not worth the $600 I originally paid for it.