Zoho
http://www.zoho.com/
Zoho is a suite of online applications (services) that you sign up for and access from our Website. The applications are free for individuals and some have a subscription fee for organizations. Zoho vision is to provide our customers (individuals, students, educators, non-profits, small and medium sized businesses) with the most comprehensive set of applications available anywhere (breadth); and for those applications to have enough features (depth) to make your user experience worthwhile.
(Text quoted from zoho.com)
ThinkFree
http://www.thinkfree.com/
ThinkFree Docs is an online community for publishers who want to share a variety of documents, spreadsheets, and presentations. ThinkFree My Office allows you enjoy instant access to your files, and share them with colleagues and friends anytime, anywhere. Document editing is fundamental.
(Text quoted from thinkfree.com)
Google Docs
http://docs.google.com/
Google Docs allows you to create basic documents from scratch or start from a template.
You can easily do all the basics, including making bulleted lists, sorting by columns, adding tables, images, comments, formulas, changing fonts and more. And it's free.
Upload your existing files - Google Docs accepts most popular file formats, including DOC, XLS, ODT, ODS, RTF, CSV, PPT, etc. So go ahead and upload your existing files.
(Text quoted from docs.google.com)
