Goodman Games is having a 3e throwback sale, most all of their 3e PDFs are $1. Castle Whiterock the megadungeon is 5 and the Dragonmech campaign setting book is $3.
Rogue-tober Sale 25% off select PDFs until Oct. 15th. Not quite sure of the theme, a lot of solo games but also Demon Gate and a bunch of 100 [X] type PDFs.
River Horse Games is having a Friendship is Magic 10th Anniversary Sale with it looks like the whole official My Little Pony RPG line is 50% off through October.