With GameSalad, "the world’s most advanced game creation tool for non-programmers," users drag-and-drop elements to create games for the iPhone or iPad. Wouldn't that make a fun library club for middle-schoolers? Create a collection of games made available to the entire school!
In fact, (older?) students could even sell their games through the App Store.
The app offers a variety of game styles, from shoot-em-ups to adventure to car racing, and the interface is clean and easy to understand. The site provides both video and text-based support.
Gaming addresses several technology and curriculum standards as students develop story-telling skills through the game narrative, problem solve, work collaboratively, and more. It's well worth the time, and would certainly be motivating for many students.
Here's a brief introductory video to give you a sense of it all!