MyBB Community Forums

There are some forum icon plugins that help you assign different icons to every forum

But they are 1.6 

Please tell me about a working one.

http://mods.mybb.com/view/forum-icons

Open Main Plugin File ficon.php

and find:

"compatibility" => "16*"

and change it to :

"compatibility" => "18*"

I have not tested this on 1.8...just showing you how to change compatibility. It may or may not work

you can try using MyForumIcons - Custom Forum Icons plugin

I use this tutorial on my 1.8 board. Works great!
http://community.mybb.com/thread-92128.html