I've spent the last couple of days adding in sharing / social networking / bookmarking tools to this blog. I don't think the process is complete. Compare the list of option currently added on the "Share and subscribe" list (about 9) to the little patchwork quilt of sharing icons that I found on another website (pictured).
While any one of these may be all someone needs as a reader, it's very frustrating as a writer. You want to provide useful tools, but there are so many competing services that it's very hard to stay on top of them all.