YouVersion is my all purpose bible app. Here you'll find devotionals and reading plans. You can also listen to, read and share the word and take notes all in the same app. A lot of churches are starting to connect with YouVersion so you can catch a message you missed on sunday.
Daughter of the King is my favorite mobile devotional at the moment. You get daily devotionals and prayers for women of God.
InstaPray is a prayer community app. You can pray for others and form prayer groups with people all across the world. You can also send words of encouragement and comment on subjects.
Fighter Verse is a verse study app. It helps you to retain God's word by using quizzes, speech recognition, songs and a home screen widget. It has over 520 verses to start, but you can add any other verses you wish.