As an exercise I am planning on building a new open source blockchain/currency completely from scratch in Java.
Rather than be one of the many clones of Bitcoin, this will be something new.
My question to you guys is: which features do you think the blockchain/currency should support?
My thought that you must try to think what your target to build a new blockchain. There is a project that builds the blockchain from scratch. you must complete what's purpose of your blockchain. If that's only to grab your investor money and forget it. you must come with something new rather than to do the similar way with another project.
Ideally I would like to create a solution that would benefit society. I am financially independent and have no interest in investor capital.
I have a background in AI and app development. Perhaps some sort of mobile aspect as suggested by @player514.
I'd love to figure out a useful POW algorithm as well. I'm thinking of how perhaps the POW could help to train AI or solve scientific problems. Open to other ideas of course.