IMO, for as much traffic as the fly fishing forum gets, another reason to visit it would be beneficial, though I don't necessarily see the need for a specific forum just for patterns.
Start posting them in there and if it gets to the point where it's hard to find the pattern information because the forum is so busy, a sub-forum could be used to organize it better.
Just my 2 cents.
"I suppose it is the way of hunters. We are very odd fellows." ~ Peter Hathaway Capstick