The pattern "movement" -- the wave of using pattern language and concepts to express process design and group behaviour strategies -- has had a hub since the early days.
This site is that hub. It has aged, though -- many of the pattern pages have been removed or are 404 :(
The original movement was concerned with bringing the concepts behind architectural patterns into software design, so most of these pages are about that. More recent patterns for Agile teams and organizational development are mostly other places.