Silly thoughts:

What about a timed escape? The contestants could be handcuffed or tied together and have to figure out how to get out. Lots of comedic opportunites...

There is a brain-teaser escape with two people and rope or string that isn't a magic trick, more of a party game. I'll see if I can find it.

Or they may have to complete other magical tasks in order to get the key to release them. Tasks like changing clothes (under covers of course) while handcuffed...

The one-handed and the 'tying a knot without letting go' are in most "stunts" type books and wouldn't give away any secrets. And there's the classic 'pulling a tablecloth from a table without breaking anything' stunt.

I am assuming these are all being done to the amusement of an onlooking audience.

S.

Excellent ideas, many many thanks guys

Okay, first of all, avoid head choppers, needle thru arm, ect.

I like the idea of escapes or rope tricks.

Also, and I am not sure if this will play well, how about "do as I do" effects. It would be fun to see how the participants would play off getting the same results as the spectators.

Whens the show David?

You could do the classic loops (cant remember the name!) but the effect is:

You have 3 large loops made from crepe paper. Each contestant merely has to cut down the centre of the loop to form two seperate loops. You do this to demonstrate. When it comes to the specs turn you can make it a race, of course neither wins as one gets two linked loops, and one gets one long loop!

You could finish this off by gathering all the loops together and producing a dove from them or whatever just to prove that you are magic!!

O.K. Show over.

Thanks for all the input everyone. There were aroung 250 people at the Wedding Fair I was advertising at and one of the reasons I wanted to do the show was to advertise my services.
I went with a short magic presentation which included cane to silks, A rope routine and then silks to cane. The contestants only had to try and recreate the rope part of the act.
Everyone seemed to enjoy the show and I did receive lots of interest in booking my show for forthcoming weddings.
Many thanks, David

The name of the effect is the Afgan Bands I believe