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.
Wikispaces names their best of 2011, including an IT blog and a history blog. Unfortunately, Warren blocks many wikis, and you may have to ask to have them unblocked, wiki by wiki
Nice interactive that shows you how countries compare relative to many features and statistics. Can be done with world as whole, US or Japan. Includes such things as population, religion, causes of death, health, education, and more.