Hone your mouse skills and try to become a master Juggler by hitting targets whilst juggling balls in the air in arcade mode. And once you've mastered the art of target hitting, see if you can achieve a high score by playing in free play mode.
[Edit] : Thanks everyone for your comments! I realize the game is hard, but I think once you get the hang of throwing the ball you can do some really neat things with the balls. I've written some hints on the Digg post for the game. You can view it here:
And if you feel so inclined you can Digg the post too :) Again, thanks for all the positive feedback!