Portaflex Wiki - great source of information on all things Portaflex. Be sure to check it out!
Second Nature - a great South Carolina band, managed by Tommie James. Tommie was my first true "customer" and his early feedback was responsible for several of the construction details that are now part of all my cabinets.
Vintage-Amp Restoration - run by Gregg Hopkins, co-author of Ampeg, the Story Behind the Sound (a must-have for any Ampeg fan).