Well, the superiority of Tit-for-Tat to most other Iterated PD strategies was discovered by evolutionary sims, and evidence has been found of its being used in nature. For instance, the behavior of WWI soldiers who stopped killing each other in the trenches by mutually choosing to only fire their artillery when fired upon first, and several instances in animals. I'm too lazy to look up the latter, but I'm pretty confident they're in The Selfish Gene. I think lessdazed is asking if there are any other important game theory findings that don't have that kind of real world support.
From memory of The Evolution of Cooperation-- the soldiers didn't refuse to fire their artillery. They aimed to miss.
Artillery truces drove the generals crazy, and they tried various solutions that I don't remember. None of the solutions worked until they discovered by accident that frequently rotating the artillery crews meant that histories of trust couldn't be developed.
Perhaps the generals could be viewed as building cooperation at their own level to maintain the killing.
This thread is for discussing anything that doesn't seem to deserve its own post.
If the resulting discussion becomes impractical to continue here, it means the topic is a promising candidate for its own thread.