We = people that don't work in the gaming industri, and has a company backing us.
Read this:
http://www.csgamezone.com/showthread.php?t=1343
What could be done really? Even if you say that this asset is "© me" there is no way to stop people from stealing your work and if you don't have any big money or a company to back you, there is nothing more to do then mail and ask them to stop, right?