In the United States, the official websites of Major League Baseball, Minor League Baseball and NCAA baseball are good places to find the latest baseball results. These sites include scoreboards that are updated after every batter, or sometimes every pitch, of every game until the final score is posted.
Sports media sites such as ESPN also post regularly updated baseball scores. Both official and unofficial sites tend to update game information quite quickly because of the newsworthiness of the information to a wide audience.
Scoreboard.com is a good resource for scores from baseball leagues outside the United States. As of 2015, the site includes scores from leagues in 23 different countries on five continents.