Words With Friends
It's always fun playing games with friends, especially when you can do it on your own time, when convenient for you. That's Words With Friends. Like Scrabble (exactly from what I can tell) this game lets you play back and forth with other friends all over the world. Play at your own pace and challenge yourself as you see fit. The free version has ads but frankly they're pretty unobtrusive. If you love the game you might want to pony up for the paid version. At 99 cents it's not a huge cost. If you love words, like games that make you think or just want to play with others without having to schedule time this is the app for you.