Open IT Online supports Google Docs, Google Apps, Zoho and ThinkFree to edit or view documents and support Snipshot, Bilder Editieren, Picnik and Pixlr to edit or view images.
This add-on handles following file formats: - Documents (.doc, .rtf, .odt, .sxw), Spreadsheets (.xls, .csv, .ods, .sxc), Presentations (.ppt, .pps, .odp, .sxi) and Images (.jpg, .gif, .png). However it does not have support to pdf files.
When Firefox encounters one of the file types mentioned above, you will get an option to open the file online. Choosing this option, you will also have the possibility to choose which online service you want to use to open the file.
Open IT Online shows you also the file size of the document you could see online, this information helps you determining if you want to open the file online or not.