Here are a few:

Coin or Money Juggling
Everyone juggles three coins each. When each person drops they leave all their coins on the floor, or put them in a hat. The last person juggling 3 coins wins everyone's money.

Simon Says Three Ball
Playing Simon Says while incorporating 3 ball juggling. If you drop, you are out, if you don't do what Simon says, you are out.

Joggling
Basically a foot race of any distance, where contestants may only advance while juggling. If a contestant drops during the race he/she must return to the point of the drop and continue again from there. This is taken very seriously by some people (in the USA) who hold meetings with all kinds of variations on the one basic idea. Even joggling with hurdles.

Three Ball Obstacle Course
Like joggling but more stupid/fun. Juggle three balls while going though an obstacle course. Chairs and caution tape make nice mazes, be creative.

Joggling relay
Good fun when mixing different types of juggling skills.

Club Gathering
The contestant is thrown clubs at the speed of a 7 club doubles passing pattern and tries to see how many he/she can catch without dropping one. As soon a one club hits the floor, they are done. For good jugglers with big arms up to 70 or 80 clubs might be needed.

Diabolo in a box
Everyone stands in a large circle and throws their diabolo in a box held in the centre. Whoever gets it in first wins.

Juggling Limbo
Juggling 3 balls (or clubs), make your way under a pole that decreases in height with each pass. If you drop, you are out. If you knock the pole off, you are out. Rules vary on whether you can touch the floor with anything but your feet.

Speed Balloon Modeling
Who can blow up a balloon and make a poodle/hat/motorbike the fastest.

Long distance club passing
One juggler stands on a line and the other walks backwards, passing 6 clubs between them. The pair that is furthest apart before they drop wins.