Thanks for the responses guys, the colour change idea is the obvious use for the flash card. I've done that effect and it gets a good responce, but it does leave a burn mark on your real card, I've also used them for going from card effects to coin routines. I force a card that matches the flash card and have the spectator put a little magic into there chosen card anyway they want ( blow on it, sprinkle magic dust, kiss it etc. etc. ). I'll have the flash card on the bottom of the deck with a double backer second from the bottom. Return the spectators card to the deck and make some cuts, controll the double backer and flash card to the top of the deck. Next do a double lift ( takes practise to get it looking right ). Show the spectator that there card came to the top of the deck, lift off just the flash card and leave the double backer on the deck ( deck goes into my pocket at the same time palm a coin from the same pocket ). Move flash card to hand with the palmed coin. Now I'll say to the spectator, lets see if the card you put magic into is really magic..light the flash card and produce the coin. Tell the spectator there card truly was magic and go into a coin routine.