Simdock is an AWN-like dock for Ubuntu. It doesn’t require a compositing manager like xcompmgr or Compiz to run, so it makes a good choice of dock for lightweight window managers.
Here’s a screenshot:

To install simdock:
sudo apt-get install simdock
To make simdock look transparent, you need to set your wallpaper as the background:
simdock -b=/path/to/wallpaper.jpg
To have it set to be above all windows, run it as so:
simdock -y
One thing simdock won’t do is place itself on all workspaces. Thankfully, if you use Openbox, there’s an easy trick. Open up ~/.config/openbox/rc.xml:
nano ~/.config/openbox/rc.xml
and place this between <applications> and </applications>:
<application class=”Simdock”>
<desktop>all></desktop>
</application>
Log out and in and the changes will take effect. Enjoy!