I just read an interesting article on CNN.com titled "How board game helped free POWs".  What was interesting about it is something I had actually never heard of before.  During WWII the British Secret Service arranged for Red Cross care packages sent to POWs to have copies of the Monopoly board game.  What made THIS version of Monopoly different was that it actually contained hidden maps made out of silk for whatever region the POW camp was in, complete with safe houses, actual currency mixed in with the play money for the purpose of bribes, a metal file and a compass. 

Because the German forces were having problems with supplies at the time, not only for their prisoners but for themselves, Red Cross care packages were more than welcome and the board game seemed as a harmless way for prisoners to toil away their day.  No one suspected that they were actually intended for escape!

The article goes on to state how Monopoly was banned in communist countries such as the USSR and Cuba because of their glamorization of Free Market Capitalism.  These countries even went so far as to create their own communism slanted knock offs, with such titles like "Save" or "Manage" in their respective languages. 

So the next time you play Monopoly and get a "Get Out Of Jail Free" card... remember... Some actually did!