If you're still playing Left 4 Dead, you're probably well aware that the 'Crash Course' episode was due for release today on Steam and Xbox Live Marketplace. If not, hey, new DLC!
To commemorate the new mini-chapter, plus the new Achievements (*drooooool*), Valve is slashing the price of the Steam version by 50%, giving you ample reason to finally own Left 4 Dead. That runs until October 2nd, giving PC gamers plenty of time to procrastinate.