If you want to try out a nice little Halloweeny themed game, you can buy the full PC game of Plants vs Zombies for only $6.99 right now.
Just pay and download your game.
I haven't played this game yet myself, but various reviews across the interwebs say that it is good fun initially, but doesn't have much replayability.
PCGamestore seems to be a fairly new digital download service. They do seem to have a few good prices as introductory offers, so should be good competition to the likes of Steam and Direct2Drive, also the game sites themselves, like Popcap games.
This reminds me of the funny ads that Popcap games created. Have you seen those annoying Evony ads all over the internet? Well, Popcap did a spoof of them to promote Plants vs Zombies. They really made me laugh! Here are a few:
THREAD UPDATE: I bought and download this last night. I think I lost about 4 hours playing it. It's fun!