Dropbox

Synchronise Any Folder
Dropbox Folder Sync is a simple app for Dropbox that allows you to seamlessly sync folders outside the Dropbox folder. Pretty handy for syncing Firefox profiles, saved games, music library, Outlook data files etc., to Dropbox directly from their locations. Sync and Unsync to Dropbox just by using the right click menu on the folder. It actually works by moving the folder into Dropbox and then putting a symlink in its place.

http://satyadeepk.in/dropbox-folder-sync/#clarification