It looks like this one's been around for a while, but Jezzball is new to us.

The basic idea is to block off sections of the game area: whenever you click the mouse, a line is drawn across the 'pitch'. If it makes it to the other side, the enclosed area is painted out, but if a ball hits it before it's painted, you lose a life.

Paint three quarters or so of the screen to move to the next level. You can play anonymously, or create an account and play against others.

That's about it: simple, but addictive.