Writely, now with Google!
I first heard about Writely in late September last year... it offered a pretty nice web-based document editing interface. It allowed semi-live collaboration. And it exported to commonly used document formats. Nice!
Of course, I don't write many collaborative documents, and those I do are usually restricted to living behind a firewall, so I didn't get far beyond testing out the live-collaboration features.
Nonetheless, Google seems to have seen how good the tool was, and decided to add it to their portfolio. I expect Google Office (or the equivalent) can't be that far off - there's a Calendar in the works, Gmail's pretty solid, and Google Base seems to be up to many hosted DB tasks.
Anyway, I went back to re-evaluate Writely, and see how they were keeping up under the renewed load caused by all the press. So far, so good... this blog post is even coming strait from a Writely document. I imagine they'll re-open for general signups soon enough.