After listening the presentation on Dropbox, I almost immediately downloaded the application. It is probably the best tool for team work purposes. In fact, I started using it in the following days.
It is way better than sending attached files through a webmail message. First, it is free for 2GB capacity which is largely enough for sending images or any document. How it works:
You download the application and you can "drop in the box" the files you want to share with anybody having installed the application. You drop documents needed for a semester project in the box and you let now to your colleague that the documents are there!
A very interesting feature Dropbox has is you can earn extra capacity storage when you refer somebody to adopt this tool...

The next application is huge to me: Google Earth.
For somebody being interested in travelling and geography, Google Earth, basically,  delivers the whole planet on my computer screen. The pedagogic possibilities are almost endless. Specially for high school international programs such webtool adds more excitement to the class. The 3D vision allows users to discover the ensemble of a city without being there physically. The virtual space that Google Earth provides may serve to travel in a class and keep the students motivated to learn and stay open minded to the world and its diversity.

I was appealed by two other Web 2.0 tools. The first is "Concept Board" (conceptboard.com
) which may improve teamwork within class.  For example seizing images, webpages and browsing them on this board could facilitate the synthesis of ideas in a group. In other words, concept board simplifies the process of building ideas.

Another webtool I found of interest is the kidblog concept. As a teacher who surveys the students' posts, he or she will be able to give immediate feedbach about writing. Receiving feedback and corrections for one's writing asserts improvement in one of the four areas of a language. Also, the authentic and engaging feature of personal writing  makes this webtool perfect for practicing grammar notions and concepts.