I was looking for a app to study for PMP certifcation for my mobile devices. As I am an apple fan so I have Iphone and ipad with me. There are penalty of PMP study material on the Appstore but I found "PMP Resource (Rise up)" very usefull. It covers all the areas and process groups and defines ITTO. It has Formula calculators and PMP glossary dictionary for quick reference. The flash card cocept is fantastic as it also challenge you to remember.