The Operating System is (Almost) Dead - Cloud applications to replace your computer applications

There are so many tools that are available via the cloud, I would claim that the operating system doesn't matter anymore.  You can be on Windows 7, Windows 8, Mac OSX, Ubuntu, or anything as long as you have a web browser and an internet connection. You can do nearly everything you need to do as a student via any web browser.

Here's a list of free applications that you can use in your web browser instead of on your computer:

• Cloud file storage
• Google Drive
• Dropbox
• SkyDrive
• Box
• Picture editing
• Aviary
• Presentations
• Google Docs Presentations
• Prezi
• Microsoft Office alternative
• Office Web - works with SkyDrive
• Google Docs - works with Google Drive
• Note taking applications
• Evernote
• Google Docs
• Springpad

Every one of these applications also had an iPhone and Android phone app.  You're not always going to be on a computer and being able to access these things via mobile applications is very important.  What cloud based applications do you use?  Please make a comment with the application(s) and how you use it for your classes.