Found this great list of C&Cs, shows and more: http://www.newenglandautoshows.com/new-england-auto-shows-master-listing/
While a useful link, I'm sure you (and others) will find the list on 603speed.com to be more comprehensive - never mind the fact that Bruce and I have a pretty large organic list of car enthusiasts within a 30 mile radius of Route 3 [from Burlington to Nashua]. Definitely makes for a more authentic experience when you get friends and acquaintances driving together on the road and/or meeting up only at dealerships.
