If your site is graphics orientated or even if its not, here a good tip to get some visitors to your site.
Put a graphics tutorial thread in your forum, explaining how to do something in photoshop.It can be anything form how you made a fancy sig to how to add shadow.
then goto
http://www.good-tutorials.com and post it there in the right section.
I did a simple tutorial, and received 1000+ visitors to the thread in 1 day. So far the thread has had over 5000 views.....
I probably didnt get many members joining as my site is not about graphics but it sure livened up the forum when it was just starting...
make sure the forum is accessible to guests when you submit it to good tutorials.
Another good tip is to change your sig to an advert for photoshop stuff or something as you may get some revenue too.