Baseball-Reference.com
Baseball-Reference.com is a website providing baseball statistics for every player in Major League Baseball history. The site is often used by major media organizations and baseball broadcasters as a source for statistics. It offers a variety of advanced baseball sabermetrics in addition to traditional baseball "counting stats".
Baseball-Reference.com is part of Sports Reference, LLC; according to an article in Street & Smith's Sports Business Journal:
History
Founder Sean Forman began developing the website while working on his Ph.D. dissertation in applied math and computational science at the University of Iowa. While writing his dissertation, he had also been writing articles on and blogging about sabermetrics. Forman's database was originally built from the Total Baseball series of baseball encyclopedias.
The website came online in April 2000, after first being launched in February 2000 as part of the website for the Big Bad Baseball Annual. It was originally built as a web interface to the Lahman Baseball Database, though it now employs a variety of data sources.