Letterpress is a touch-input game for iOS devices by Loren Brichter. It combines the territorial control of game like Othello with Boggle's hunt for unique, polysyllabic words. It app store description puts it succinctly: "Find words, steal tiles, color the board!"
The game is notable for its fast, fluid UI and its sudden popularity– after leading multitudes of players to join Apple's "Game Center, it managed to temporarily bring the cloud service down due to the game's popularity.
Letterpress is ad-free, free to play, and has 99 cent upgrade which enables more than 3 games to be played simultaneously. If it surprises you that this is something you might want to do, then you probably haven't played Letterpress yet.