The Pinball Pasture is one of the oldest and most comprehensive sites on the 'Net. Fairly long list of rulesheets. Features include the fictional House of the Dead 2 machine, video clips on the production of Xenon's sounds, and a personal collection. A historical pinball fan site complete with photos, sounds, software simulations, and links. Lots of information, pictures and flyers on post-WW2 pitch and bat games, and pinball games with mechanical animation.
Collector buys games too.
This site has extensive repair and restoration guides for most pinball machines from 1947 to present. A small collection of flyers for sorted by manufacturer. Includes photos, rules and links. Also has information about new games soon to be released, tournaments and shows, and pinball links. Help build the largest human-edited directory on the web.