Someone earlier mentioned PD's Adult Magic book then discussion went on to his TV series using ESP cards.
In Adult Magic he details an effect using 34 half cards where 2 spectators each choose a half card. When they are both tabled they match up.
Gochos, if this is the same effect you are after get PD's Adult Magic book. I've seen it often on Ebay, don't know if its still in print.
And yes Kat, for you young wippersnappers out there, we really did used to have mobile phones like the one PH is holding on page 154
