My middle schoolers love Animoto. I just found Voice Thread which I think is a great way to collaborate. I could not live without United Streaming and Discovery Science Connection. I have used Bubbl.us for brainstorming. Google Docs is great for collaborating. My students love SoundSnap - free sound effects for podcasting. Zamzar is a free online file converter.
Our community has a shared "buzka". Mostly about EFL (English as a foreign language) teaching but look at the Web 2.0 spot. Might be something there and buzka itself is a super cool bookmarking site! http://eflclassroom.buzka.com
One of the best finds in a long time for me was coming across a beta called "Jing" by Tech Smith. I give a demo of how you might use it in the classroom here -- http://web20intheclassroom.blogspot.com/2007/11/best-find-in-longlo.... At the same site I try to share out all the other cool finds that I come across. Hope something benefits you in some way.
Hi Jennifer~ I run a site called ChitChat (http://ChitCh.at) that we just recently launched to help teachers share content and make it easier for them to assign, collect, evaluate, and offer feedback on student work via the web. I hate to be too commercial, but since you're looking, I thought I'd let you know about it. If you have any questions, let me know!