Let's say you teach across multiple computers or even in multiple locations.
In the ever so likely event that a CD or USB disk fails (or gets lost) and you don't have hard copies on hand, or you need to edit and print something from a PC bang, you can use one of these websites.
Zoho.
http://www.zoho.com. It's a suite site that's got everything important from spreadsheets, writer (a little clunky but effective), spreadsheet, and docs management (if you just need to load or print something without editing) among other goodies. You can upload almost anything to it (pptx doesn't work yet). You can import and export files to and from Open Office and I believe they have a plugin for Microsoft office now as well.
Google Docs. About the same as Zoho, only with more features. If you already have a google account like Gmail, I believe you don't need to create a new one. IF you do have gmail and you use this in class, make sure to log off after you leave or your students will check your e-mail and send each other spam mail in your name.
slideshare.net. Got a presentation like pptx and it don't work on either? Or just need something to work when the school computers won' t load it. Load it into
http://www.slideshare.net/upload and you can have your presentation ready to go in class when all else (except internet of course) fails.
There are probably other methods to deal with classroom files and such, but these methods have worked for me in the past. I hope they work for you the reader as well.
