What's the rarest or most unusual computer-related item do you own?

I have a certificate that my father was given in 1957 for training on a Honeywell Datamatic 1000 computer. Here is a summary of this 'advance' in computer technology from the ACM: The DATAmatic 1000 (D-1000) is a high-capacity electronic data-processing system designed specifically for application to the increasingly complex problems and procedures of present-day business. The system incorporates significant new systems techniques, as well as several basically new component developments. One of the outstanding features of the D-1000 is its ability to feed information from magnetic tape into the central processor at a sustained rate of 60,000 decimal-digits per second, and to deliver data after processing back to magnetic tape at this same rate. The operational speed of the central processor maintains full compatibility with the high speed of information transfer. Consequently, the difficulties caused by programs which are either tape limited or processing-time limited do not arise in the majority of commercial applications of this system.