My Lines is an app that can serve as a valuable tool for memorizing lines, presenting the script in a way that shows the lines of the actor's role separate from those of the rest of the cast. This is very helpful for students to memorize lines for a monologue or play they are working on.

http://itunes.apple.com/us/app/my-lines/id393204594?mt=8
Requirements: Compatible with iPhone, iPod touch, and iPad. Requires iOS 3.0 or later
Price: $9.99