My 8 year old son has been wanting his daddy to build him a chin up bar.  It's a little tall yet, but he manages to jump up and reach it.  He'll grow into it soon.  He has fun on it, but he sure does scare me sometimes, hanging upside down with no hands 6 feet above the ground.

(half of it's painted, my husband started to paint it, then my son
got mad because he was trying to play on it and couldn't if it was wet)