I came across a site not that long ago that was using the shared spreadsheet of Google docs in a pretty creative way to achieve something like this. Of course, I can't find the site now

It might also have involved Google's app engine, but that is heading into coder skill territory.

Google free form maker - there looks like some interesting options out there.
Maybe someone passing through might also have some ideas, and I'll scratch around for more info when I get a gap. I've also got something I'd like to develop along these lines - but unfortunately it's quite far down the to-do list just at the moment.