Gary,
I recently heard someone mention that they use alias within their Dropbox folder that point to other folders. This allows them to use Dropbox to back up their files in the cloud without always uses Dropbox itself to replace their documents folder.
Hope I explained it right. It sounds interesting. Could you comment or elaborate on this?
— Michelle
See http://wiki.dropbox.com/TipsAndTricks/SyncOtherFolders for some info on this. Basically, it looks like you can't just use a plain Alias to do this. It is much more technical.