Technorati is certainly comprehensive and well used! When I searched for "learning 2.0" on Blog posts I got 499 hits. Using Blog Directory, I Clicked through Technology then Web 2.0 and got 13 pages of hits arranged with the highest authority first which I thought was useful. I then went into a blog and noticed there were four versions of "web 2.0" used as tags, (i.e. web2.0, web 2.0, web20, web 20). Clicking on the link through "web 2.0" brought up 14,678 hits! Interesting stuff out there but abit overwelming.