Climbing is another subject deserving of a guide, but it is worth noting which areas are worth researching.
Rumney has become famous in recent years and is heralded as one of the best sport climbing areas in the country. With hundreds of climbs, ranging in difficulty from 5.3 to 5.15+, there is something for every sport climber. This area is very popular, and especially on Saturday in the summer you may find yourself waiting for the most popular, especially intermediate and expert level climbs. There is a Rumney guide, again available for purchase in any local bookstore, that describes each climb and assigns it a difficulty level. This is especially helpful for less experienced climbers or those who have never been to this area before, as the "sweet-spot" of Rumney is the 5.8+ range. If you can climb at the 5.10 level or higher it may even just both worth showing up and checking it out, talk to local climbers, and see what looks fun.
No matter your level, it is worth heading over to the Waimea Rock (one of the many areas of Rumney, each themed and often clustering around a certain difficulty level). Waimea is where many of the best climbers spend the day working project routes, mostly 5.12+. You may even see some famous climbers here, as more and more climbing movies are filming clips at Rumney. There is also excellent bouldering.
In addition to great skiing and hiking, Franconia Notch is home to legendary climbing. Cannon Mountain is home only to traditional climbing, both in the winter and summer. In the summer, routes range from 5.4/5 to 5.12+. However, despite some relatively easy climbs, Cannon is a challenging mountain due to loose rock and quickly changing weather conditions, and is suited only to experienced climbers who are comfortable with setting traditional pro (if you do not know what that means, its not for you). There is also a lot of history at Cannon Mountain, with a lot of pioneering climbing happening here. Many top-notch climbers from the northeast consider this their training ground, as the harsh conditions prepare them for more committing, high-altitude climbs elsewhere. If you run into any old-timer climbers at the top or in the parking lot, have a chat with them. The guys who literally wrote the guidebook are still around and putting up new routes.