Three mental-magic effects I perform always are the following:
3 Card Surprise: Bob Long - World's Greatest Card Tricks
Spec (or 3) select cards to which you have already made predictions for prior. In the end, your three predictions match the three selected cards.
I modified my handling to be a bit more natural and fair looking.
Gemini Twins: Karl Fulves- More Self-Working Card Tricks
You make two open predictions. Spectator deals down twice and stops freely wherever you want. You pull their selections and show your predictions. They match.
This is a variation of Twin Souls found in Encyclopedia of Card Tricks y Jean Hugard.
Unknown Coin Prediction Effect: Max Maven - Videomind series
I can't recall the name of the effect and it doesn't appear to me when viewing the content listings for the DVDs' product listing. But this is the effect (I have seen a number of versions of this using gimmicked envelopes or himber wallets) but I first came across the effect from Maven. Not sure where it origionates.
Your give your spectators three imaginary coins. They pick one out aloud, and toss it. They tell you which side it landed on (heads or tales). Then you show your prediction. Which tells which coin landed which side up, and it matches the spec's freely imagined coin.
All three are completely impromptu, and give me some of the best reactions ever.