You mentioned two things - a. really light b. really stong to witstand the track abuse. I instantly thought about VOLKS. They are light and very well constructed. As for the specs what you should get, I don't know too much about it. Please make a thread in the wheel/tire section.
Check out these lightweight rims on the AE Performance's car. I think they are awesome:
http://www.the370z.com/members-370z-...z-project.html (BTW, I can't view ANY image since I'm behind a firewall at a office but I think these are lightweight rims. I will double check when I go home)