On top of Tim's tribute threads, I especially liked the other pic threads (e.g. Kyle's thread on Ballyneal, Tommy's Woodhall Spa, Patrick's Lahinch tribute, Mark's Alwoodley, Scott's Portmarnock, Ed's St.Enodoc and John's Maidstone to name just a few).
For some of the older courses or restorations/renovations, I especially like the before and after pics (e.g. like Ian's Lookout Point - Ian where did the pics go?, Mike's Lake Merced 8th, and especially Dan's Lawsonia)
I especially liked Bradley's discovery of the MacKenzie photos. Great stuff there. It's like finding a pirate's treasure chest or something.
I wish we had more threads on Colt, so I was happy to see a little love from Alfonso's Evolution of HS Colt as an architect.
Mike's Cobb's Creek is still going and attests to the interest. Wow! For different reasons David's Merion was interesting and ... memorable. I don't think I've seen a thread like David's create so many spin-off threads...
Chip's unbelievable golf trail was very cool to witness.
The KP thread was good fun as usual.
I'll second Kyle's mention of Art's delicious.com reference.
I'm already forgetting plenty others, but so it goes...