+ for Diigo. I want most stuff private, it does it. You can create private groups, which I use as folders, say if doing research on an idea I throw all the re

+ for Diigo. I want most stuff private, it does it. You can create private groups, which I use as folders, say if doing research on an idea I throw all the related bookmarks in a private group. Then I can also share the collection, by just letting someone in the group. They have very robust browser extensions as well.