A little card they give you to say that you're an inmate / student at a school.
Woo! an update! I've just noded descriptions of some student IDs I have in my posession:
My old school (and all the other schools in the Salt Lake City School District used cheap laminated cards from high school. The cards were built around a backplate bearing the school's name and seal. Upon this card was pasted a photograph and a label with my name, grade, and ID number. The label appears to have come from a sheet of sticky labels that were printed on a nine-pin printer. After application of the label and photograph the card was run through a laminator. There are places on the card to stick a sticker indicating that the card is valid and a sticker to indicate that the owner is allowed internet access at school.
The ID issued by my current school is of similar construction to a credit card. Before the recent ID conversion (the current IDs are known as U-Cards), IDs were printed on blank cards via some sort of machine at the ID desk. The current card may have been printed on a similar machine, but I'm not certain, because production occured offsite. On the front the card bears my photograph, name, student ID, library number, and a printed representation of the number encoded on the card's magnetic stripe. Since the card is a smartcard, there is a gold terminal on the front to communicate with the chip inside. Currently the smartcard functionality can only be used for a digital cash implementation, but there is supposedly space for other things. The card is valid as a bus pas for UTA busses and light rail. The card is starting to show wear from the magstripe reader in the door locks, and the white of the card's plastic is starting to show in places under the photo.