A few months back, after checking out the options available, I switched over to using Diigo.  It offers more options, and has some nice grouping features.  Also, I primarily use it because it can send links to delicious every time I make a new bookmark, and would import from delicious when I started, but delicious doesn’t offer the same options.  This way I have a backup of my bookmarks, as well as access to tools that interact with delicious.  This way, too, if I’ ever someplace that blocks one but not the other, I won’t find myself lost in the middle of a lake without a paddle. Like most of the social networking tools, I more or less exclusively use it as a professional resource.  I do the personal posting thing in Twitter to some degree because everybody does, and it’s what makes the community a way of getting to know people, but I’m really there for interacting with other educators.  This blog primarily, but not always, deals with education.  Any nings I belong to are education-related, and of the major social networking sites, the only one I’m on is LinkedIn, a professional resource.  Diigo is the same for me.  It’s all about things tangentially related to education.