What additional social networking referral buttons do you recommend?

I'm referring to those colorful little buttons that are as of this post in the upper right corner of every post under the mini-heading:
Use these buttons to tell others about this post

They're a great way for telling other people on the web about a specific post that you find particularly beneficial or descriptive of what this Forum is all about.

Please use them a lot. It helps spread the word about this work, and invites other like-minded, like-motivated people to our discussion here.

All you need do is click on a button and it has built into its link a link back from that particular social networking site to this post.

In effect, you're telling all the people who will see the entry at that website about the particular post here that you think is worth checking out.

You do usually need to register the first time at any particular site but after that the process is pretty automatic. Use pseudonyms whenever possible or desirable in the registration at those sites.

Thanks for helping spread the word about the benefits of this practice, and what it means to you.

Jack