Paradox Interactive is hosting a sale running from Friday 25th to Monday the 28th of November. You can get started over here.
Most of the big games like Magicka, Cities in Motion, Mount & Blade: With Fire and Sword, Hearts of Iron III, Europa Universalis III Complete and King Arthur: The Roleplaying Wargame are 60% off.
So if you are an avid Paradox fan, you better get started.