One scenario that we have experimented with is red torch, green torch.  
It is a particularly twisted activity based on the old elementary school
game of red light, green light.

In this scenario, there is a treasure that everyone wants, either a
princess, a mound of gold, magic item, glory, something like that.
There is also a magical torch with two ends.  A weapon that can be marked
as red a green on opposite ends works well.  We've used an orange-tipped 
Javelin with a piece of green cloth tied to one end.

The treasure is free to move about the battle field at all times, and
idealy, they carry the torch.  When the RED end of the torch is up,
everyone is free to run after the treasure.  When the GREEN end is up,
everyone (except the treasure) must freeze (or attempt to freeze) exactly
where they are.

While this may sound silly, and it probably is, the whole thing can be
quite fun.  Since the objective is to acquire the treasure, it follows
that fighters may want to kill each other in order to increase their
chances.

There are several possible variations on the logistics of the torch.  I
think the best is that the torch has a limited number of uses, and the
stopping power only lasts for a limited time, 15 seconds for example.

Try it at Rag if you get bored and let me know how things go.

		Vonkar of Aerostoren, from Anfalas