There were some attempts at actually doing useful work with all that proof of work:
http://primecoin.io/ and a detailed article about it https://bitcoinmagazine.com/articles/primecoin-the-cryptocur...
http://primecoin.io/ and a detailed article about it https://bitcoinmagazine.com/articles/primecoin-the-cryptocur...
I really wish coins like these would catch on more than they have. Proof-of-work is, to the best of my knowledge, the only system that provably works. If we could just harness that computational power to do useful work, we'd be in a great place.