Smokin, I have a site with a discussion forum, as well, and photos are a HUGE part of that forum. People like to see pictures of whatever a person is talking about. I was considering changing the forum software that I use, but my current forum software is the only one I have found that will allow members to upload directly to the forum without sending it to me, or without having to link from an external server. That was the single biggest factor in choosing and keeping my existing forum software. I can't imagine how much of an administrative nightmare it would be to have people sending photos for me to resize, upload and send a link so they could post to the forum. I'd also guess that having to do so is a major deterrent to visitors posting pics on this site.
Provide an easy way for users to directly upload pics, and I believe you'll see a dramatic increase in participation on the forums.
Michael