With the development of Google Docs (http://docs.google.com/), one has to do word processing on their computer less and less. Working online is usually faster (just a browser to load), and allows your data to be stored in “the cloud”–that is, online rather than on your computer, making the files more secure.
However, for mathematicians there has always been a problem with this–LaTeX. Many of us use LaTeX to write everything. Academic papers, tests and exams, assignments, and even worksheets and letters (my CV was even made in LaTeX). Because of this there has not been much opportunity to switch over to using Google Docs (or any other online office suite). But as more websites are being created, more Web 2.0 apps are being written, we have today some nice options.