Pandemic, a cooperative board game that you can play solo (by controlling all four players) is discounted on the Appstore for Ipad.
http://appshopper.com/games/pandemic-the-board-game
There are also various Fighting Fantasy gamebook implementations for the Ipad which are marked down from $5.99 to $1.99. They're pretty awesome implementations as they include music that fits the mood, and some other options.
http://appshopper.com/games/gamebook-adventures-1-an-assassin-in-orlandes
http://appshopper.com/search/?search=gamebooks
Happy Thanksgiving all!