Tammy Worcester has a list here of her top 20 web tools.
Here are my favorites:
Build songs quickly and easily for free online, similar to Garageband. Students love to rap and write songs!
Skitch (Mac) / Jing (Mac/Windows)
Skitch is a simple screencapture program for mac. The annotations are the best feature, which gives a simple way to add arrows and text to your screen shots.
(Similar to Twitter, only threaded)
Please find me on Plurk, I plan to grow another learning network here for edtech.
Tammy is an iGoogle and Google Reader fan! I’ll be sure to dig through her feeds!