Have you heard of Bitsboard?

Bitsboard is a free app for iPads and iPhones. The games are fairly simple brain games that many kids are familiar with like word search, scrambled words, flashcards, etc.  The games are good for building spelling, reading, and word recognition, as well as vocabulary.  There are also games about parts of speech, and much more!  The format of the games also encourage critical thinking.  You can track your students progress, too.  There are also math games and math classes available, including multiplication facts, but the focus of this app is more on developing reading skills.  These games can also be great for ELL's who are working to boost their English vocabulary.   

 Here is a fairly thorough video of how the app works to navigate and play the games.

Here's a video demonstrating how to create your own boards, so that you can customize the words that students will work on.