Check out these fun skip counting games:
http://www.sheppardsoftware.com/mathgames/earlymath/BalloonPopSkip.htm
http://www.abcya.com/number_bubble_skip_counting.htm
http://www.sheppardsoftware.com/mathgames/earlymath/Fruit_shoot_SkipCount.htm
http://www.education.com/games/skip-counting-game-show/
http://members.learningplanet.com/act/count/free.asp
http://www.sheppardsoftware.com/mathgames/earlymath/BalloonPopSkip.htm
http://www.abcya.com/number_bubble_skip_counting.htm
http://www.sheppardsoftware.com/mathgames/earlymath/Fruit_shoot_SkipCount.htm
http://www.education.com/games/skip-counting-game-show/
http://members.learningplanet.com/act/count/free.asp