The best part about Quakerism, in my opinion, is that it teaches a very hearty disrespect of un-earned authority without teaching disrespect for the concept of authority itself. One of my favorite anecdotes is a group of Quakers who refused to doff their hats for the King, as they only doff their hats for God.
There's another old practice of refusing to swear on the Bible before telling the truth, as that would imply that they weren't telling the truth before they were sworn in.
I find the inclusion of Zen in this article is interesting, as you won't find the word "Holy" or "God", used, and "Spirit" is only used twice, once to comment on how he felt pressured to receive a message from it. The original purpose of Quaker silent worship was to remove the church-imposed barrier between man and God (the "Holy Spirit") so that anyone could be a mouthpiece for the wishes and desires of the Spirit. Modern American Quakers, especially the ones who write in Friends Journal, tend to be pretty secular.