That really depends on what you are looking for.
If you are trying to understand the biology and the psychology behind your teenager I would recommend The Primal Teenage Brain by Barbara Strauch.
If you are raising young children and what to know some things we have found in research studies that could help try Nurture Shock by Po Bronson and Ashley Merryman.
If you are looking for insights into how to help children who have undergone trauma try The Boy Who Was Raised as a Dog by Bruce Perry.
If you are looking for mind stimulation or stress reduction I would recommend looking into UCLA's mindful awareness program. Some details are available on the web.
Other Psychology favorites are Blink, Freakanomics, and Musicophilia.