http://trademarkbureau.com/trademark_classes.php
It doesn't seem to stop National Geographic from licensing their logo to optical instrument manufacturer Bresser.
Yellow border on electronic hardware: http://www.bresser.de/publications/national_geo_kat_de_en/HT...
[EDIT] There are some
Class 9 (including electric): http://trademarks.justia.com/852/58/n-a-85258337.html
Class 16: http://trademarks.justia.com/850/51/n-a-85051489.html
http://trademarkbureau.com/trademark_classes.php