Just read Web 2.0 A New Wave of Innovation for Teaching and Learning? By Bryan Alexander. To start off with I liked how the article explained what web 2.0 is or is not. Including items like social bookmarking, wiki pages, collaborative writing, blogging, blog and RSS search services--where users can create micro content about micro content.
A few places I plan on checking out when I have time:
http://www.daypop.com/ (would not open at school)
http://www.memeorandum.com/ (blocked at my school)
I liked how in the article it talked about several of the ways web 2.0 could be valuable to higher education. For me, this is key, if I am to spend time learning about a new technology I need to know how to implement it in my classroom or if it is worth implementing in my classroom.