Visual Pinball  
   A PC pinball emulator where you can more or less faithfully reproduce the gameplay of most tables created before 1990.
   http://www.randydavis.com/vp/

IR Pinball  
   Downloads of Visual Pinball recreations of classic pinball tables (1920-1980). New tables continually released.
   http://irpinball.ztnet.com/

Visual Pinball Forums  
   A moderated discussion forum about Visual Pinball, Visual PinMAME, other computer pinball simulations, and real-life pinball tables. High signal-to-noise ratio.
   http://www.vpforums.com/

Magic of Flipperless  
   Flipperless pinball history and visual pinball re-creations.
   http://www.saharasales.com/flipperless/

ShivaSite  
   Among other things, a clearinghouse for all VP-related content. Focus is on creating new tables, but also has an upload/download section available after you register.
   http://www.shivasite.com/