After a little bit of work, I was able to put together a folder icon for the Dropbox folder that is inline with the design of the home folder icon.

I’ve not created all of the icons to be used for this, only the one that you will see in Nautilus or your file browser, but I may eventually make the others as well.
Thanks to some work from Dropbox user “Charles A.“, I was able to modify a folder icon and add the themed icons.

Feel free to take what I’ve done and extend it further or improve on it! I’m by no means an artist. 😉
If you modify this icon, I only ask that you mention me and pass me a link to your improvements!
–Download (v0.1: 193kb)
EDIT: I’ve updated the package to include all 4 icons for images of (square) sizes 16, 22, 24, 32, 48, 64. You can grab the updated package below.
–Download (v0.2: 343.4kb)