There are new releases for the 5E and PFRPG rulesets and a sale running on the core license, D&D Complete Core Monster Pack, D&D Lost Mine of Phandelver and stacked discounts for those last two products for people that Complete the Set on the D&D bundle.
Sale
20% off (45% as part of the D&D Complete the Set Bundle):
http://store.steampowered.com/app/360090/
http://store.steampowered.com/app/360114/
Get it as part of the Complete the Set bundle to get 25% off everything in the bundle and 45% off the two products above. If you already have some of these, you only need to pick up the rest to get the discount on those items.
http://store.steampowered.com/bundle/256/
New Releases
Tarin's Crown is a short adventure for 5E targeted at 6th level characters and would fit perfectly in any island or seafaring campaign.
http://store.steampowered.com/app/471310/
The Sinking Complete Serial
A massive, epic adventure that takes your players from level 1 to level 11. It is one of the top selling module series of all time from 0One Games.
http://store.steampowered.com/app/469940