One more little hidden feature of Dropbox you may enjoy, particularly when editing pictures on-the-fly.
Dropbox supports a "time machine" sort of file backup. If you store an original file in your Dropbox, then edit it and re-save it using the same file name as the original, in most cases you will forever lose your original. In Dropbox, you can use their website to go back and selectively restore older versions of the same file. I've used this a couple of times and its saved my bacon when I accidentally saved a large Excel model, overwriting the prior version (that turned out to have the correct data).