Juxio--multimedia communication (facebook, twitter, email) Lots of potential here for communication--could, for example, send home for updates on class work (digital mulitmedia news letter).
podcasting in classroom--good introduction; lots of ideas of using audio (e.g., embedding in Word). Instructional delivery (e.g., could use this for 504 plans).
Reviews lots of podcasting Web 2.0 tools. Good point--limit student audio recording. Discusses editing and when to use.
mp3 collection of 'free' stories and poems; can search by author, title, reading level, content. All have PDF of passage so can be read as listened to.
Tag cloud creators--great summary all on one place (e.g., Wordle). I have used several and find them pretty straightforward to use. (Note Tagful will only give 1 month free--so use the 'free' sources.)
Just wanted to show you how diigo works. This is a timeline feature that has lots of possibilities (e.g., if you are watching beans sprout, you could record their observations for a science report).