[work in progress] Syncronising dropbox and google docs

In order to improve productivity of sharing files, I'm looking for a way to syncronise my dropbox folder and google docs. There doesn't seem to be a proper way to directly connect them, so I think they should be connected thorugh another application or service.

I thought cyberduck could be a good solution, but I cannot figure out how to automatically update files from dropbox, which means when I edit files in dropbox, it seemed to me that I need to upload the edited file.
http://cyberduck.ch/

Then, although I just tried a free personal version, syncplicity may be another way, but it also didn't upload a file edited on local.
http://www.syncplicity.com/
This might not be good for sync with google docs but back up.

However, they seem to be a good solution to syncronise your files with cloudsourcing services.