Hey, I still have a small stack of free admission USAir Club passes from a US sales manager (remember when they had those??!?). He gave me about 2 dozen of the things and, back in the day, when I was connecting in PIT all the time, I'd use one for a long layover.
Still have maybe 5 or 6 knocking around still. Used one last year and the agent commented that she hadn't seen one like it in 7 years or so, but had no further question. We were waved right in.