Many users would love to have a more purpose-defined folder icon like Pictures or Documents folders, etc.
Mathieu Comandon over @The Hacking Capybara has created a set of replacement icons specifically this reason (including for a few other folder types, too) and boy do they look nice!
Grab the .tar file @ LINK SINCE BROKEN.
Installing is painless.
- Extract the downloaded archive and move the icons somewhere safe
- Right click on your Ubuntu One folder and choose properties
- Click the folder icon the upper left corner and navigate to the ubuntuonefolder.svg you extracted previously.
Image by Mathieu Comandon