Palladium has an Alternate Realities Sale 20% off 11 PDFs showing off the Palladium Multiverse including Rifts, Rifts Chaos Earth, the Palladium Fantasy RPG, Recon (the Vietnam war RPG), Nightbane, and Systems Failure.
The Blight is a great corrupt city 925 page sourcebook for $12.19, but check out the massive 952 page Orcus themed wasteland ruined city sandbox Slumbering Tsar Saga for $3.75. If you ever wanted to check out a sandboxy mega-adventure now is a great opportunity.
The Cyclopean Deeps are also great deals for a little more than $3 each for 160 and 250 pages of Descent into the Depths underdark sandboxing.
Over at the non halloween sale for FG's pathfinder line Razor Coast colonialism pirates themed mega-adventure is still a ridiculous steal at $2.50.