[freebreakfast]

I think Gridcoin offers a happy medium. It's proof of stake, but it also offers rewards for participating in BOINC-based research projects.

https://gridcoin.us/

Not exactly "proof of work" in the same sense its being used, but I wish that the project would get more attention.

[Forbo]

I've been trying to get people to pay attention to this project for years. I think a lot of the "useful computation" chains are much more likely to survive the next cryptocurrency crash because of their inherent utility. For example, the various storage coins, stuff like Nym or Oxen, Namecoin, etc.