I wanted to mention that ScoreCloud, which converts what you sing or play into music notation (including time signature and key), is now available on the iPad. It is officially called ScoreCloud Express HD. To convert the output to other formats, it has to be uploaded to the ScoreCloud website (a basic membership is free but limited). The app is currently $0.99. The developer promises that the iPad app will have future functionality (I am not sure if that will come as an in-app purchase), but right now functions the same as the iPhone app–but is optimized for the screen of the iPad. I like seeing what ScoreCloud does when I sing (or play) at it, and for that reason, I think it is worth buying. There are definitely pedagogical possibilities with this app (think of the assessment of sight reading, for example).
Here is a link to ScoreCloud Express HD (as always, a referral link):