http://min.us/This term I have to teach my fourth grade students in their various home rooms, and so have to rely on my USB stick to ferry my lesson materials from place to place. Occasionally some of the PCs will refuse to accept the drive or be too slow to use etc. As a precaution I make a zip file of all my materials and upload them to min.us. It's as simple as dragging the actual zip file into the browser window - the upload speeds are lightning fast compared to google docs or MSN skydrive, which is what I was using before. The site generates a short URL to access the file, and if you sign up you can keep galleries of your material to access as you wish.
I've found this very useful, and I much prefer using it to having to log in to my personal google account on other teacher's computers. Not that I don't trust them or anything...
