At 14, he may be old enough for much of what you will find here...
http://chartporn.org/"A collection of interesting charts, tables, maps, and interactive data toys -- with a focus on economics and graphic design."
This is the link that introduced me to the site back in the spring:
http://chartporn.org/2010/04/16/so-you-need-a-typeface/Sorry about the name...
ETA:
http://visualoop.tumblr.com/A little more family-friendly name, to be sure.
Also, in the lower-left column, you'll find links to a dozen or so similarly-themed sites.
Your son's appreciation for charts is shared by many.
