From the Paul Harris Presents series comes this great impromptu trick. In effect, you kneel down and cause the two loops of someone's shoelace to link together. The only way to unlink them is for the participant to untie their lace. You do this once more, leaving the two loops completely tied together.
I like it for a very specific reason: it's a personal trick. It's not like most tricks where the audience just sit and watch the magician. Instead, they're involved in the action because the magic is happening to them. I can only think of a few effects that meet that criteria, so this one is definitely an impromptu keeper.
The other great thing to keep in mind is that this is completely impromptu. There are no gimmicks, or other things to carry around. You can just kneel down and perform it on anyone and at any time.
Watch the video to see David Jockisch perform the effect. You probably won't be massively fooled, but I think your audiences will be.
Comes with 28 page, photo-illustrated instruction book and DVD.