I have been carrying around my expired transpasses because, well, after a while it seemed like bad form to start throwing them away. For now, at the end of each month, I tuck the old one into a small plastic pocket on my craptastic freebie "briefcase." (The dude got it at a conference. The lettering has worn away, I can't even tell you which it was, though you can still see "Pittsburgh 2005" on it.)
The passes are plastic, but not as thick as a credit card. I have them from September 2005 when I was living in Exton and paying $170 to commute to the city every month and will continue to accrue them at a significantly reduced cost (and commute time). They are very colorful and I can probably remove the "F" stickers (they go where the sample says "not valid" so they know a chick's supposed to use it). One has a hole in it from the time they punched it (they can do that) during the SEPTA strike. The "Anywhere" passes have iridescent bits too, probably to avoid counterfeiting since they are so valuable. The cards are about 2"x3" and I have 24 of them (and counting).
What can they become now? Any ideas?