www.abrsm.org/speedshifter is a new app (also available for desktop) which allows you to play backing tracks / CD tracks / MP3 files at any speed you want – without altering the pitch.
http://www.musicroom.com/blog/music-education/music-theory-for-beginners is an excellent app for ipad / iphone (maybe other smart phones ….. I’m not sure at present) to practice music theory. It’s not a free app, but it has lessons and quizzes of a wide standard, so there will be plenty to learn 🙂
