Google has an entire office suite online called Google Docs. You can create documents, spreadsheets and presentations completely within your web browser. I find this great for stuff that I need to have access to from many computers. All of the apps have nearly all of the features that you’ve come to expect from a desktop application, and a few that you just can’t get. For example, there’s a widget in the spreadsheet app that will mark up a Google map with a list of location’s that’s in your spreadsheet. This is a fun little toy to play with in my spreadsheet that tracks all of the traveling that I’ve done for work.
Bonus Tip: You can use Google Docs from your phone. Any phone can view documents, and some higher end phones can even make edits to documents.