Marvel Heroes is an excellent f2p arpg from the creator of Diablo 2. One amazing thing they've done is to not only consistently add content and tune the game, but to also hold promotional weekends with extra free stuff. They've recently decided to make the weekend long promotions a week long as often as they can to accommodate more people.
Starting today they're having a weeklong event where they have 10 of their previous promotions all running at the same time.
To bring it back to deals, one of the promotions is buy 1 get 1 random on either costumes or heroes.
You can also use Steam credit to buy in-game currency and you'll get a card for every $9 spent.