Kromm is one of the authors of GURPS Fourth Edition's Basic Set. He is, in general, considered to be "the source" for rulings regarding GURPS tule questions. He is the brain behind (through not the compiler of) the Kromm Notes, which can be found at http://www.krommnotes.org/. The Kromm Notes are a list of additional rule clarifications. They are not up to date on the 4th Edition at the moment, though new notes are coming in.

His profile, from the Steve Jackson Games Forums, is up there: http://forums.sjgames.com/member.php?u=5

Dawn of Magic , a website run by Ellie The Technomancer, details the fantasy campaign run by Kromm in a Roman, TL2, universe. The weekly recaps are especially interesting! And in this thread he posted the stats for the player characters. A very cool insight into how Kromm uses the rules.