Just pointing out the spread cull force - it seems to me that it's by far the most realistic force that I know - it looks to the spectators just as if they touched any card, and got that card.
For those who don't know it, I'll try to explain it, vaguely.
Cull the force card under the spread, and get them to touch any card. Out jog the one they touch (saying, "This one?") but keep it face down. Split the spread into two with their card supposedly on the bottom of one, and load the culled card onto the bottom of the stack.
I find it looks much more convincing than a riffle force or something similar, because the vic...spectator (subconsciously?) knows that they could touch any card.
Just to point it out

Kati