This blog entry from Steven Anderson highlights some of his favorite livebinders (and he's somewhat of an expert). There are also other valuable posts on his blog.
This particular entry addresses twitter, but there are many great things on this blog. How cool that a husband and wife blog together (can't imagine that happening at my house!) They include various resources, including history and elementary ed.
Great teacher blog. Great way to develop a culture of readers. Like idea of students posting what they've read/are reading. Whatever Wednesday. Friday book trailers.