Online productivity applications have become quite common in the past few years, and while they won't likely supplant traditional desktop office suites (like Microsoft Office) anytime soon, the two examples I used while working on this "thing" were surprisingly versatile.
Zoho Apps and Google Documents are both very competent productivity suites in their own rights, and while they may not pack in all the features of a desktop sutie, I would argue that's not necessarily a bad thing. What each leaves out is for good reason. For example, both Zoho Writer and Google Docs' word processor provide far more than the basic text editing tools normally associated with the Web; both have LaTeX-based math equation editors, collaboration tools, page layout options, and support a number of different file formats, including the Microsoft Open XML formats, like .docx, .xlsx, etc. Don't expect more advanced features like mail merge or complex cross-reference tools in the free online versions (although the paid business versions do have some of these features). Still, in my opinion, either of these online productivity suites would cover 95% of the average user's needs.
For comparisons of Zoho Writer and Google Docs and examples from each, keep reading after the jump!