I'd be there, and a Photoshop-sub would be excellent for this forum I think. Since a lot of patching is depending on a good program (and everyone and their uncle uses Photoshop...) it would be nice to get idea/tips/pointer/showcase stuff.
I understand the arguments put forth by Andrew, but I don't buy in to them fully. A sub-forum wouldn't be amongst the most used but I think it could raise the bar of the forum alltogether.
1. More patchers would get better.
The patching-sections doesn't have a natural place for small pointers and such, a individual forum would make this easier. And a plce for individual stickies for FAQ's (like blend modes and so on..((I dunno, just making it up as I go, don't blame the examples.

))
2. Better sigs
This doesn't matter for shit, but it's fun
3. More activity
Marginally, but still. I can only speak for myself, but I would rather post that kind of questions here than to add yet another forum to my "visit-and-post-to-get-answers-and-stuff-to-your-questions"-list.