Like the title says, the World of Darkness Rulebook, in PDF, for free. No idea how long it's going to last, but it's there.

All the World of Darkness games need the rulebook (unsurprisingly), so for people who haven't seen a game but might want to check out Hunter, or indeed just want a cool modern horror game, this is a steal.

(Thanks to jesshartley for the tip.)

Must have been a bug, as the link's now very dead. Sorry.

mythicfox pointed out the correct link, so thanks to him. There's also Scion: Hero for those who prefer crunchy mythic games.