What was the largest transaction fee ever paid? Assuming that payment was an accident was the sender able to contact the miner who mined that block and negotiate a full or partial refund?
This transaction (2016-04-26) has even higher fees (291.2409 BTC).
This plot shows transaction fees higher than 1000USD from the past 3 years. From the plot, the April 2016 transaction seems to be the one paying the highest fee.
I think this one: http://btc.blockr.io/tx/info/4ed20e0768124bc67dc684d57941be1482ccdaa45dadb64be12afba8c8554537 - 200 BTC fee!
It was an accidental fee scooped up by ASICMiner, but they refunded the guy.