I picked up some ticket-in ticket-out vouchers while in town for the convention. I don't collect them, but will trade them for almost anything you've got. Here's what I've got:

Circus Circus - "Cashout Voucher" One Club & Circus Circus logos on back
Circus Circus - "Cashout Voucher" No logo on back
Palms - "Cashout Ticket" With logo on back (2 of these)
Palms - "Cashout Voucher" With logo on back (3 of these)
Riviera - "Cashout Voucher" with logo on back
Stardust - "Cashout Ticket" with logo on back
Treasure Island - "Cashout Ticket" 1 with light gray logo, 2 with dark gray logo
Treasure Island - "Gaming Voucher" 3 with logo on back