EvilHat.Com: Article discussing ways to "right-size" villains who turned out too effective or not effective enough.
Guardians Of Order: Official site for the game. Includes errata, a preview of the Authority sourcebook, and discussion boards. Also features downloadable character sheets, quick start rules and upcoming products.
Silver Age Sentinels - Draxzaster.com: Campaign notes and a character generator.
Yahoo Groups - Silver Age Sentinels: Unmoderated discussion maintained by Guardians of Order.