Steam and GoG are both having an Activision sale. While Steam focuses mainly on CoD, GoG seems to have the everything, including Arcanum, Phantasmagoria 1 & 2 and Vampire the Masquerade Redemption. Both are selling King's Quest and Space Quest games. but GoG breaks them up into two packs and it's cheaper to buy the whole thing on Steam.
Steam also has Vampire the Masquerade Bloodlines on sale, which means the patch broke it. However a NEW patch has already been uploaded.
Steam, GoG and Steam still have all things Star Wars on Sale.
Humble is having a Ubisoft sale
Greenmangaming doesn't have any sort of special sale going on, but it has it's normal deals.
And again, not games, but today is free comicbook day and Drivethrough RPG has a fuckton of free comics right now.