Ibrahim Arabic Keyboard This is the best Arabic keyboard for Android hands down according to all my fluent Arabic friends.

Speak Arabic Free This free version will teach you to speak useful Arabic phrases by category so that you learn functional Arabic for travel, leisure, and business. Has some errors, though - and is limited.

English-Arabic Translator This app works very well for translating from English to Arabic and back. A must-have.

Arabic Quotes This is a good way to learn the language of Arabic and the culture at the same time. These are a set of quotes from all over the Arabic world.

Arabic Alphabet Learn the Arabic Alphabet with this app. It's colorful, fun, and will totally make the letters stick in your mind. Recommend.