If your radio uses shortwave, you might be in luck. Many countries (at least used to) broadcast time on the same frequencies as the US. 2500, 5000, 10000, 15000 KHz. One wiki page mentions some radio frequencies currently used but definitely in the past there were MUCH more. There probably still are but it isn't listed.

http://en.wikipedia.org/wiki/Radio_clock

BTW, this reminds me of how warped I used to be, listening to those stations for hours at a time. "At the tone, __ hours ___ minutes coordinative universal time. BEEEEEM boom boom boom boom click click duuun click click click ". Especially funny was listening to both Colorado and Hawaii (or other countries) at the same time. Hours of entertainment indeed. The scary thing is that I enjoyed listening to it almost as much as listening to transpacific air traffic.