In Gossamer Forum 1.1.5 and 1.1.6, you can enter HTML directly in the forum description field - so you could simply enter a forum description that looks something like:
<img src="/pics/some_image.gif"> My Forum Description
Jason Rhinelander
Gossamer Threads
jason@gossamer-threads.com
Code:
<img src="/pics/some_image.gif"> My Forum Description
Jason Rhinelander
Gossamer Threads
jason@gossamer-threads.com