www.jalopyjournal.com (For my 1936 Ford) Also refered to as HAMB.
www.benzworld.org ( just for my 1966 Mercedes) Lots of traffic and postings in the vintage benz forum.
www.mbca.org (Mercedes)
does craigslist count.
Always seem to be looking for an interesting car.
There are others, just not someplace I go to daily.
For Porsche content, only here.
-- brett