Basically a very good and powerful text editor, which was easy to use. I tested ZOHO with a conference paper I wrote on Measuring-Library-20
that included tables, images, and citations. I had some issues with ZOHO 's apparent lack of functionality to format tables, do footnotes, and to do hanging indents (which means I would be reluctant to move from MS Word for anything that required serious formatting) but the ZOHO Writer is very good for simple documents. This exercise also demonstrated how bad long and complex documents look when posted into Blogger - but then why would you post a 4,000 word document into a blog?!?
The other ZOHO applications, in particular Zoho Meeting for Web Conferencing, Zoho Notebook an online note taker, and Zoho Projects for project management look particularly interesting. I'm not sure about the chat as to date I have found chat works best when integrated into a social networking site as is the case in Facebook.