Uncle Joe was the first person in our family to go to college (the
University of Connecticut, to be specific). One fall day circa 1960, our
family packed up the Chevy and drove to Storrs--the home of "UConn"--with
cans of Spam and other delicacies to deliver to Uncle Joe. When we caught up
with him, he gave us the grand tour of the campus including his dormitory.
Two things in his dorm impressed me: the first copy of Mad magazine I had
ever seen (the famous fly swatter issue #57) and a shortwave radio tuned to
a station whose sole purpose was to tell the time.

The National Institute of Standards and Technology (NIST) Time and Frequency
Division Web site is the home of the folks who keep time at WWV, WWVB and
WWVH...

See this interesting article about "radio stations that have time" in full
at http://www.arrl.org/news/features/2004/08/13/1/?nc=1