Somewhat related, though the exhibits aren't as nice- The National Cryptologic Museum in Maryland. If nothing else, it's an excuse to venture on to the grounds at Ft. Meade.

When I visited a number of years back, there was a guy selling cell phones on a little folding table outside the front door. Which seemed...odd...for any number of reasons, given the location.

http://www.nsa.gov/about/cryptologic_heritage/museum/