Sports Economics

The following are some websites found that may provide useful information. 

General Sports Information:

Baseball, Basketball, Hockey and Football Online Statistics Databases
Ballparks.com
Journal of Sports Economics (abstracts of articles)
Links to all sports
The Sports Economist

Professional Baseball Information:

Baseball Economics Resources
Baseball-Links.com – All Sorts of Baseball Links
Baseball-Reference.com – Major League Baseball Statistics and History
Baseball Think Factory
Business of Baseball – The Baseball Archive
Major League Baseball : Official Info : Home
Major League Baseball : Official Info : Official Rules
The Business of Baseball

Professional Basketball Information:

Basketball-Reference.com – Professional Basketball Statistics and History
BasketballReference.com – NBA Basketball Statistics, Draft, Awards, and History
NBA data
The Business of Basketball

Professional Football Information:

Pro Football Reference.com
The Football Database
The Business of Football

Professional Golf Information:

ESPN.com – GOLF – Statistics
PGA
USGA
Professional Hockey Information:

NHL Stats Database
The Business of Hockey
The Internet Hockey Database