So Google Docs...
It started out as a simple online document creator and storage and promptly took off into the coolest most universal collaborative online tool out there.
You can upload word, excel, powerpoint and pdf files from your computer for sharing, viewing, and editing. You can also create these documents directly on the cloud!
For Mac users, you can upload pages and numbers as well but they can not be edited or viewed directly on the cloud. They CAN be stored however, and downloaded wherever you will need them.
Google also just added video capabilities. So you can now upload any of your video files (up to 1GB) to be stored, viewed and shared!
But the BEST part? Collaboration!!!
You can simultaneously access the same document as your collaborator. You can actually watch each other highlight and edit in REAL TIME!! Gone are the days of a million copies of one document getting emailed back and forth, trying to keep the versions straight. Google docs lets you work of ONE copy and it saves a version history so you can either reference the older version, or revert back to it entirely. This has been a brilliant tool when working with students on their papers, and collaborating with classmates on group work. Turn on google chat/vid chat (or skype, aim, whatever your fancy) and you can have your group meeting without actually having to meet!
Now you tell me, why WOULDN'T you use that?!