Way off in September, the American Hiking Society is sponsoring a volunteer project on the Appalachian Trail in Maine. See the details here.
I have blogged about my trail monitoring here before. Just do a search to find the most recent post or an earlier one. Here is a shot from my recent trip.
AT Corridor Monument 246 MA 23 in Tyringham Valley, Massachusetts.
Can't make this one? Try another volunteer project. I am sure a local hiking club needs some help.