There is a game called "Brain cube" or something like that, I really liked it.
As for an App, "What's App" is a great one, it's like BBM but instead, you can text to any other Smartphone user who installed it.
My opinion is that the classical games like "Tetris" is the best.
There are some more that I liked, "Reversi" is great, it's like Othello, or "Best Dots" is fun, or the addictive "Bubble Birds", that's the few that raced my mind right now!