AGH Museum - http://www.atarihq.com/museum/coinops/index.html
Museum that displays old Atari coin operated games. Has images of the various game on show.
Highwaygames - http://highwaygames.com/
Features news and information regarding the amusement and leisure industries. Also includes references and articles.
RePlay - http://www.replaymag.com/
A monthly magazine for news and information on the coin-op industry. Includes subscription details and resources.