Sleeping Giant State Park does not just have great hiking, it also has great climbing and bouldering. Pick up the blue trail starting at the backside of the visitor center. This trail climbs pretty steadily but take note that as you hike up the cliff below you is a great spot to checkout for bouldering and some top roping or trad climbing. 

When you get to the top of the mountain by the overlooks you'll find a good boulder to tackle (marked with a 13). Since I could not find any name or info online of it I am calling it Blue 13, rating - v2, because there are some tricky fingertip holds. 

Once you have played around on Blue 13, continue to follow the blue blazed trail down and then across the carriage road. You will see another big rock formation that has some great problems to explore and create yourself. The landing area is a bit sloped so you'll have to be strategic on where to put your crash pad. I did not tackle this area because I was lacking a crash pad at the time. 

Final spot to check out on the blue trail is about .2 miles past the second rock formation. This area is a cross between bouldering and free climbing. The height of the rock is probably 30-35 feet with a big crack up the left side. For this route we started right of the tree, climbed up and left passing in between the rock and the tree, then up the crack the rest of the way to the top. We called this route, Ryan Got Stuck, i'll let you all guess why we called it that. Rating - v2 or 5.6 depending on how you want to look at it in terms of bouldering or free climbing. 

These areas are just a few spots to try but there are a bunch of other areas in the park that i am sure have great rock to climb. For trad climbing or top roping you will definitely want to try the cliffs at the "Head" of Sleeping Giant.