On May 29, 1905, Cardinals shortstop Dave Brain tied a modern day major league record by tripling three times during a 6-3 victory over the Pirates at Exposition Park in Pittsburgh. Less than a month after this game was played a story appeared in the Pittsburgh Press that had Brain expressing his discontent with the Cardinals organization and rumors were running rampant about him being traded. The rumors became true on July 4th of that season, as he was dealt to those same Pirates he victimized on that day in late May. Brain made a bit of history with the Buccos by completing the three triple feat in a game on August 8th of that same season making him the only player to do it twice in one season. Since 1900 there have been 48 games in which a player tripled three times. It has only been achieved by one other Cardinals player, with that being "Sunny" Jim Bottomley who joined the club in 1923. Two men tripled four times in a contest before the modern era began, with those being George Streif of the Philadelphia Athletics in 1885 and Bill Joyce in 1897 as a member of the New York Giants.
The Society of American Baseball Research published a great piece about three triples in a game that you can read here: http://research.sabr.org/journals/three-triples
You can also read Dave Brain's SABR biography here: http://sabr.org/bioproj/person/8d0440ac