The leak from October 10 was correct, which means Steam's Halloween sale has been kicked off as of yesterday. Until November 3 you'll be able to buy lots of games at discounted prices, stocking up your backlog some more.
The theme is, of course, games with something of a horror aspect to them, such as Alan Wake, Dead Rising 3 and Dead Space. Check out the full list for yourself on Steam to see if there's something that might get you in that Halloween state of mind.