Sortable is a visual approach to triumph, perfect for walkaround. The spectators can see the cards being mashed face-up into face-down.

A card is selected, and optionally signed. Then the deck is shuffled by both the magician AND the spectator. Next, the deck is mashed together face up into face down. It's clearly a mess.

Finally, with no suspicious moves, all the cards magically turn face up... except for the selected card.