Tennis Open 2007 feat. Lleyton Hewitt is an extremely impressive achievement in mobile racket sports. For one thing, the game crams more minigames, tournaments, and modes into one tiny download than I thought was possible. For another, it's probably the only mobile game I've played that features a control set-up that uses the entire numeric keypad.
Nokia N70, 6600, 7610, 6630, 3230, 6680, N72, 3250, 6681, 6670.