Lightbulbs, Lighting and Lamps. A short, semi-scholarly review of the development of lightbulbs, with numerous links to the inventors.
Sirlampsalot Publications, a commercial site. The home page contains links to antique lamp catalogs and ephemera. [This site has changed greatly over the years but there are still some good illustrations of antique lamps to be found here. JRW, 2/11/13]
Genuine Antique Lighting, a commercial pictorial resource for old lighting fixtures. Especially useful for designers.
Stage Lighting Bibliography and Lighting Design Source. "LightingDesignSource is a resource for lighting design students at the University of Virginia." Not recently updated, but an excellent bibliographic and information resource.