Pieter Hintjens is a huge inspiration to me, even though I've never met him in person. I have yet to find a statement of his that I don't agree with. He writes technical documentation in a no-bullshit way that is very easy to read and understand. You really feel smarter after going through his writings.
His life-long accomplishments in building open source community and ZeroMQ legacy is impressive.
It was really painful to read his blogs for last few months, especially the Fighting Cancer piece (http://hintjens.com/blog:123). I'm sad to see him gone.