If you are new to the world of Web 2.0 and are looking for a good introduction you might want to check out Mark Marino’s talk. Mark recently did a presentation at USC which covered a range of internet tools that one might consider for teaching and research. The link is to his write up from the talk, with accompanying links to the slides and resources. You can also get the full audio/video from the presentation (note to Mac users, use Firefox, I had several problems with Safari and streaming this presentation). Throughout the course of the talk Mark and Holly Willis, the Director for the Institute of Media Literacy, cover everything from annotating websites, to Zotero, and many things in the middle (Citeulike, feedreaders, Diigo, pageflakes). The presentation runs a little over an hour, but is worth your time.