Sauron's One Ring, only there's a fencepost bug in the code and it makes the person standing next to you invisible
Also the DRM on the other rings that enables the One Ring to "in the darkness bind them" has been cracked and they're on bittorrent now so LOL sucker
@cstross You can only do magic by summoning up a d[a]emon, which you can only do if you know its true name. There's a grimoire (in two volumes, called "apropos" and "man"), but they're cryptic and sometimes wrong, and if you get the incantation wrong, the daemon you summon will eat your soul^H^H^H^Hdata.