Major League Baseball: Official Rules - Complete rules of major league baseball, with diagrams and glossary. - http://www.mlb.com/NASApp/mlb/mlb/official_info/official_rules/foreword.jsp
Jim's Baseball Rules - Little League - Provides a myriad of baseball rules and regulations, FAQs, umpiring tips, myths and links. Gathered by a certified Little League umpire and former Chief Umpire for California District 3. - http://eteamz.active.com/baseball/rules/obr/index.cfm?
Baseball Umpires Rules and Interpertation - Major League Baseball rules, interpertations, questions and answers, newsletter, do's and don't on the playing field - http://baseballumpires.com
Pony Baseball and Softball - Official site includes affiliated members links, news, calendar, tournaments, and World Series coverage. - http://www.pony.org/
Interactive Baseball Rules - Seeks to create a fun environment for baseball umpires, players, coaches and fans to enhance their understanding of the rules of the game. Offers online quiz, along with rules/officiating resources. - http://www.macroweb.com/ibrules/index.html
Amateur Baseball Umpire - Contains information on baseball umpiring and officiating. - http://www.amateurumpire.com/
Official Communications - Offers baseball rules and officiating videotapes. Features online shopping and video previews. - http://www.officialcom.com/