Other game companies are reacting to WotC's no-notice yanking of their pdfs online with various promotions of their own. Here are just a few you may want to check out:
-Paizo is offering all Pathfinder PDFs for 35% off through the end of April.
-White Wolf is offering the Exalted 2e PHB for free through April 12, as well as a one-time 10% discount on any PDF product.
-Adventure Games Publishing currently has 16 products on sale through May 23 as a sign of customer appreciation.
-One Bad Egg has every pdf product on sale for at least 10% off.
-Evil Hat's Don't Lose Your Mind has been marked down to $10.
-Green Ronin is offering their True 20 Roleplaying for only $9.99.
-Bards & Sages is offering their Karma Roleplaying System products for 10% off.
-Tabletop Adventures is discounting 20% off their products for the rest of this week (thanks, Mark!).
-Reality Deviant Production is also offering a sale for the occasion at RPGNow.
-The superhero RPG Hearts & Souls is marked down to only $5.
-As mentioned in the comments below, Flying Mice is also running specials at RPGNow.
-Eden Studios is running a PDF Lovers sale--all their pdfs are 50% off at RPGNow.
-HinterWelt Enterprises is running all pdfs at 50% through the end of the month, and the print+pdf of Roma Imperious True 20 is only $19.99 ($10 off).
-Phil Reed announced all Whispering Vault pdfs are 50% off through the middle of next week.
As you find more, please let me know and I'll post them up here!