If you have a Mac with an SSD, and limited storage space, and use Dropbox, you may want to think about how much space your Dropbox folder takes up on your disk. Jeff Carlson, writing at TidBITS, had this problem, wanting to use Dropbox's Camera Upload feature on his MacBook Pro, but not wanting to have the space taken up on his SSD.
The solution he explains is relatively simple: it involves creating a symlink for the folder in question after moving it to another disk or volume. After moving the folder, open Terminal, then type:
cd ~/Dropbox
Type ln -s, then drag the folder from its new location into the Terminal window, which will add its path; press Return.
Mac OS X Hints
http://hints.macworld.com/article.php?story=20130528021327793