UPDATE: Steam also has the Call of Duty Definitive Edition for 50% off, which includes every single Call of Duty, DLC, and Micro DLC for just $200 this weekend only. Details here. (via @WePlayCOD)
Steam has launched a Call of Duty Franchise sale, giving 50% off on all Call of Duty titles ever released on PC from today until September 1st. Visit the Franchise Page here to see all the prices. You can also get all three Modern Warfare titles for $70 here.
Steam has also announced that you can play Call of Duty: Ghosts Multiplayer free this weekend until Sunday, August 31st at 1pm ET. Also, all Call of Duty: Ghosts DLC is 50% off, including every micro item and DLC pack as well.
Also, steam has added a brand new item called the Call of Duty: Ghosts Complete Bundle, which gives you the three DLC packs for Ghosts, all the micro items, and the game itself for just $90 until September 1st.