Thing 9. Online Collaboration Tools

I think Google Docs and Zoho are pretty handy resources. My wife is a librarian and her shop uses Zoho for collaboration on certain projects. It's a lot easier to have access to a document that way, instead of having to email it back and forth. I wonder, though, how hard it is to track changes that are made. It would seem that any online tool like Google Docs, etc., should offer a utility that would track changes mades, allow the original document to viewed, etc. Maybe something like Wikipedia, where you can view all the edits made to an entry, who did 'em and at what time/date. I'll have to explore a bit to find out just what Google and Zoho have along that line. Of course, there's also the issues of security and storage: how secure are documents sitting on servers somewhere and what would happen if a company were to go under?