Not replace, but enhance for web-based collaboration. For instance, in Writely, I can upload or save OpenOffice Writer documents. The other three applications that I mentioned are for online web collaboration, not to replace OOo (I guess I wasn't very clear).

For small businesses, I think that a simple, straightforward suite like OOo is a good desktop application. You can then enhance this tool with some web apps for collaborative projects. The money that you have saved on you office suite can be used for any paid web services that you may specifically need. E.g. if you share a lot of photos, you may want a Flickr professional account.

I've been using OOo for four years now and it meets all of my desktop office application needs. Lately though, many of my applications are migrating to the web.