Tuning eye tubes in 1930's Radios
This excellent site played a large role in the inspiration for this site, and has a great wealth of historical, technical, and troubleshooting information.
A very informative site with all kinds of tubes, data, and great pictures and animations.
Mike's Electric stuff
Another very informative site with all kinds of tubes. Very neat counting tubes, nixies, display tubes, great pictures, and animations.
Japanese Magic Eyes
A wonderful site by Koji Hayashi with pictures and data for magic eye tubes. Many nice japanese antique radios may be found here as well.
Precise dB Monitoring with Eye Tubes
An interesting article in PDF format written by Joe Sousa that appeared in the November 2006 issue of audioXpress magazine.