PCGameStore and Steam are having sales on Plants vs. Zombies. PCGameStore has the title available for $6.99 and Steam has it for $9.99. The usual price for the title is $19.99 so your saving 50% or more depending on which service you decide to purchase it from.
If you haven’t heard of Plants vs. Zombies before, its a tower defense game where you use living plants to fend off hordes of zombies. I’ve never personally played it but I have heard nothing but good things about it. The song is pretty catchy too.