Mt Watatic is one of New England's lost Ski Areas and you can read about its history on NELSAP (http://www.nelsap.org/ma/watatic.html). It's a popular backcountry skiing and snowboarding destination.
But it also provides some great mountain biking. If you miss longer climbs and downhills in the Massachussets and southern NH area you'll like Mt Watatic. The access road is the best way to get to the top. From there you can decent some of the old ski trails (most of them are rather overgrown) or ride the start of the WAPAC trail (yellow triangle blazes).
If you take a right off the WAPAC you can circle back to the based of the mountain on snowmobile/ATV trails.