Took Younger Nephew climbing yesterday. It was a hoot. He did some bouldering for a bit while I spotted him, and then did some top rope climbing with me belaying. He had a bit of fear of heights, but he dealt with it very well - he climbed partway up the wall, and had me lower him a bit, and then climbed up a bit higher and had me lower him a bit...repeat until he got to the top. (He also asked me at one point if I could climb with him so he could hold my hand and not be scared. Sadly, that is just not possible.) He also spent a lot of time just running around Planet Granite looking at everything - I think the idea of a place full of nothing but surfaces to climb on was very near a personal vision of heaven for him.
Younger Nephew also treated me to an extensive description of how to play Angry Birds Go! Seriously, I think it was the first time I've ever heard Younger Nephew speak in paragraphs.