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.