Good anecdote for lessons on Internet research best practices. The right answer is not always going to be at the top or even on the first page of results!
Clear presentation, quick and easy to get going. Jing allows you to capture a certain portion of the screen, which I find useful when creating a demo of the Graphing Calc, but the upload and link process is easier in this system. I think Catherine O would like this one.
Ones I've seen are Pommie, but worthwhile. Useful to use for individual teachers or for discussion at a school PD. Huge variety of topics covering Across-the-school situations to specific subject areas