So, apparently the European Country of Bulgaria is sitting on 210,000 BTC, worth roughly a couple Billion if they were to try and convert their HODL over to Euros.
According to the article I've linked below, they could repay about 20% of their public debt, which is a rather significant move for a Country which is amongst the poorest of European nations.
http://www.novinite.com/articles/186380/Bulgaria%20Could%20Cause%20a%20Global%20Collapse%20of%20Bitcoin