Thunderstone Randomizer. I added the Doomgate Legion expansion cards as well as the promos from the Promo Pack (I had already included the Clan Promo and the Death Sentinel Promo in the previous release). I like the way it has turned out so far, though I'm less happy with the code backing the web page. Too many moving parts and validation pieces make it a pain to update and each new set that gets added makes the testing for combinations / correctness a huge pain in the butt (permutations are a pain to test).
With Dragonspire hitting the shelves, I'll probably update this again soon while the little nuances are still fresh in my head. Then I'll go check and see what the other apps are offering and what suggestions / features people have asked for. I need to figure out the Google API for databases so I can add a feature to save card sets after you generate them (that way if you find a really good combination, you can replay it). I suppose I'll have to figure out some logic for making a "smart" deck builder (for the wimpy people out there that have to have items and heroes that directly match up to the monster cards).