General virtual reality (I like many others have migrated for work. It'd be nice to give my parents a real hug through the web)
Open source computer brain interface (I want Emacs but for all corporal senses)
Provably valid crypto-elections (Let's say I have a dispute with my local neighborhood about garden gnomes, we can all vote and agree on a binding solution and have no doubts about the legitimacy of the outcome)
Personal and private bioinformatics (Let me sequence my own genome without the usual Silicon Valley Big Brother using my God-given DNA for secondary purposes). Your own DNA is not implicitly copyrightable by yourself under American law, correct me if I'm wrong.