The biggest web2.0 tool that I use is moodle. I have been using this to deliver all my courses for 4 years. I use it to give students access to lectures, give & receive assignments, share online resources, give exams, and make announcements.
Zoho is a great online tool for collaboration. In my experience it’s multi-user editing is much better than Google docs’ has been. It also has many other tools available, whenever I have given a group assignment I have suggested that students use it to write their project.
I use Rcampus to make and use rubrics for my classes. I also embed these rubrics into the assignments so that students know what I am looking for.
Eventually I will be integrating student blogs into my classes I believe that this will allow them to not only get used to using online comunication, but will also allow them to explore different ways to share their drawings.
Personally I have just started using Dropbox to sync my laptop with my office computer. I was tired of going to work on a lecture, and not having the most current version, or not having a supporting file that I needed. I also use evernote to take notes (pictures of things) that I want to remember later.