Open IT Online, an add-on for Firefox, delivers you what you want.  Well, it delivers you what you want, if you are one of those people who love all these new Online services such as Zoho’s office applications or Google Docs.  Open IT Online allows you to open your documents and images online without the need of any software to be installed.
Here are some of the extension types it can recognize and handle:

Documents (*.doc, *.rtf, *.odt, *.sxw)
Spreadsheets (*.xls, *.csv, [...]

I like the PDF format and so do a heck of a lot of other people. It is as close to an “alternative standard” as you can get. It might not be used for everything, but what it is used for – it is used well. How would you like to be able to convert to PDF right from Firefox?
All you need to do is download the LOOP for Firefox extension! Yet another good power tool [...]