Entourage by Gordon Bean
Your audience names ANY queen, and it's the only card you have. The rest are jokers! Not only that, they pick the card blindly from the packet. High interactivity, and HUGE reactions.
Ishihara Test by Liam Levanon
They see 5 cards, front and back. They're all CLEARLY grey. After a "color-blindness test", somehow they can finally see their super bright colors. Everything is examinable!
Predicshuns by Roddy McGhie
One of the most charming tricks we've ever seen, Predicshuns lets you use a child’s drawing to reveal a FREELY named card! .