The Sugoi Japanese Funny Cartoon is great!
There are actually three apps and if you are learning Japanese go ahead and get them all.
Watch funny cartoons in Japanese, read, and listen to native Japanese speakers. If you don't know any Japanese you may want to combine this with a language course like LiveMocha or your Japanese classes at school. Look at how many cartoons you can watch. It's free, too!
This is a fun puzzle game where you put together the faces of the characters and every time you place a character, it is read out loud to you!
In the writing game, you can choose different characters and practice your strokes. This one is a lot of fun. Grace (my Japanese-American best friend) and I played it together and we couldn't stop laughing!