Micro blogging - personal network - personal learning network - Twitter is the backbone of most EduNerds PNL these days. How cool is this - now you can follow MC Hammer. Interesting times. Twitter is a great collaborative tool, and great communication for groups to collaborate or micro/live blog.
Edmodo - micro bloging - ideal starter blogging for junior high school - learning to use courseware effectively - and also for journal entries in PBL. In Alpha testing.