My son has an Itouch and we have searched for many free apps. Here are the ones we have on his device, Basic Math, which works on math facts; Matches, for visual spacial; Liberty of Congress virtual tour; Dictionary, to look up words; Funny Flashcards, to recognize words, A Bee See sight word, for the lower readers to practice their sight words.
How I would use the I-touch would be to have it in a center for them to explore the desire apps that were differentiated for them. Even with the Internet connect they could look up information for a report or project they are working on. Also, my team will probably have lots of ideas that we will be sharing during our planning time.