It was always frustrating for me that the UbuntuOne indicator icon was bright orange, it never fitted in with elementary at all. I put this icon together to somewhat rectify the issue. The menu still appears the same this just replaces the icon.
Download the 'UbuntuOne Indicator.zip' file
Inside should be a folder called 'UbuntuOne Indicator'
Place this folder in the ~/.icons directory (This is a hidden folder in your home directory. To show, right click and then Show Hidden Files.)
To activate, use the elementary tweaks settings plug.
USE INDICATOR ICON ALONGSIDE ANOTHER ICON SET:
Inside the UbuntuOne Indicator file there is a folder named 'Apps' and inside that two folders named '48' and 'scalable'.
Both folders contain 3 identical .svg files with different names.
Find the folder that contains the icons of the set you wish to use. This will either be in '~/.icons' or '/usr/share/icons'
Copy the icons from the 'UbuntuOne Indicator/apps/48' into the '[insert icon set name]/apps/48'
After copying the icons across, enable the icon set and the new UbuntuOne indicator will appear
GET ELEMENTARY TWEAKS:
In a terminal,
sudo apt-add-repository ppa:versable/elementary-update
sudo apt-get update
sudo apt-get install elementary-tweaks
If you are using any other OS, you can use appropriate tweak tools such as Ubuntu tweak etc
INSTALLING UBUNTUONE INDICATOR: (for Ubuntu 12.04 based OSs)
In a terminal,
sudo add-apt-repository ppa:rye/ubuntuone-extras
sudo apt-get update && sudo apt-get install indicator-ubuntuone
EDIT: Not sure if that PPA is still active. Hopefully it is as it seems the only good way of interacting directly with the UbuntuOne client without opening the whole program.. I've sent a message to Roman Yepishev asking about future updates.