Imperial Insignia: Stormtroopers: Concise overview of Stormtrooper uniforms and designations, with photographs, from the Star Wars Technical Commentaries.
Star Wars: Stormtroopers: Armored shock troops of the Empire. Official page.
TK-421 Fan Club: Tribute to that hero of the hangars, TK-421, who wasn't at his post. FAQ and small photo gallery.