I've spent most of today prepping for a series of upcoming workshops on using web2.0 applications. Some of the invaluable tools I use every day and will talk about are:
del.icio.us to bookmark sites for each workshop, to provide resource suggestions to students.
jing, skitch and kwout to mark up and annotate screenshots. I just discovered kwout and love the way it links back to the original page. I can see using this a lot when I put up information for students in the school blog. Here's an example: