Consignment tickets are available from the Pass Bureau, which is a fancy way of saying discount tickets to (generally) theme parks. Last I checked they had Sea World SAN, Knott's Berry Farm, Six Flags Magic Mountain, and Walt Disney World available. The full list may be found under Perks on theHub.
Scroll about half way down to the section titled "Consignment Tickets". Per the Pass Bureau, any employee may take advantage of this offer by either visiting in person, or via mail. Enclose a check or money order payable to US Airways, and include your badge # and Driver's License on the check. They also require a SASE to send them back to you. These tickets are actual media, so I would recommend putting a tracking # or insurance on the return envelope.
The address is:
Pass Bureau
US Airways/CH-PSB
4000 E Sky Harbor Blvd
Phoenix, AZ 85034
Of course, leave youself enough time for the mailing.