After long hours spent immobile with monitor and keyboard, nothing beats an afternoon, a day, or a weekend biking or hiking or climbing or skiing (depending on the weather, of course). To that end, I am a long-time member of the McGill Outdoors Club (formerly, to the confusion of some, the McGill Outing Club). Highly recommended if you're new in Montreal and looking to get out of town for a crunchy-granola-good-ol'-time.
When I lived in the Washington DC area (from 1998 to 2000), I was a member of the Potomac Appalachian Trail Club , which maintains the AT (Appalachian Trail) and a bunch of other trails in Virginia, West Virginia, Maryland, and a bit of Pennsylvania, as well as publishing maps and guidebooks. Oh yeah, they also have a ski touring section and mountaineering section for the ski bums and climbing bums.