Server signature is now available for everyone, i'll just show with pictures where to get it and how to use it.
Thats pretty simple.
Go to serverlist , choose the server you are interested in , check bottom infos to get the signature code.
(click on the picture to see fullsize)
Once you clicked on server signature you should get this :
Copy the code & insert it to your signature for example , using the " Insert Image" function
Which gives :
Tips : select your image(double click on it) then add a link example : http://et.trackbase.net/server/41109/
So if you click on your signature , you are redirected to your server page.