1. A method comprising: displaying a message to a passenger receiving a ride in a taxicab, in which the message offers a voucher which is redeemable for credits at a casino, in which the voucher may be redeemed for a first value of credits; charging the passenger a second value for the voucher and the ride, in which the second value is less than the first value, whereby the first value and the second value define a discount for the voucher; and outputting a receipt that represents the voucher, in which the receipt includes indicia indicating the first value and the casino.