Even if you haven't turned your NES into a DVD player, you probably still have that one game you'll never play again. With just a screwdriver and a bit of soldering, you can mod its cartridge into a wireless router with personality.
The idea itself is very simple; you just open up the cartridge, take out the circuitry, and replace it with a Belkin wireless router (though I'm sure any router of your choice would work). The soldering, unfortunately, is necessary with most routers because the circuit board of most routers is just too darn big to fit inside an NES cartridge. So, you'll have to remove the capacitors and rewire the board a little bit, but you end up with something pretty neat and retro:
Hit the link for detailed instructions, and let us know your favorite NES hacks in the comments.
NES Cartridge Wireless Router [The Unconventional Hacker]