The only irritation with the add-on is that the browser interface button takes up a whole toolbar of its own, wasting screen space.

Despite its name, the gPDF is an add-on designed to allow the quick and easy viewing of office files within Firefox, including but not limited to PDFs. It's extremely simple to use: once installed, single-clicking any link within a Web page that points to a PDF, Word document (both .doc and .docx), Excel spreadsheet (.xls and .xlsx), or PowerPoint presentation (.ppt and .pptx) will open them in the Google Docs viewer. Clicking rich-text files (.rtf), comma-separated value spreadsheets (.csv) or OpenOffice.org files will open them in Zoho Viewer.

In both cases you don't need to have a Google Docs or Zoho Office account, or be logged into them.

Thanks to gPDF, for most office documents there's no longer any need to download and view them in the relevant program, which can take a lot of time.