Glass and Porcelain Insulators Reference site
Old Insulators – many info about glass and porcelain insulators, related sites, auctions and sales
Buzz’s webpage about insulators
Brad & Susan awesome website dedicated of collecting vintage and antique and their eBay store for hand-curated antique, vintage, gently used and new goods from the heart of America.
Collector’s page on Facebook with rare insulators of Poland and Germany