I went to Six Flags over Texas last year. One had the option of renting a Fast Pass "pager". If you rented this device (Q-bot) then you went up to their "FastPass" (or whatever it they call it) dispenser and waved the Q-bot in from of it, and your reservation was made. When it was time the Qbot would page you. You could only do the fast pass if you rented the QBot (about $10 per person, 1 Q-bot per group). Few people rented them, so there was never a wait to get on anything.