Fangraphs has a collection of some of the best baseball writers (young and old) around. They write excellent columns and analyses of current baseball events, and they have a collection of stats that is unrivaled by anyone. I go here for all of my baseball news instead of ESPN, which I find to be biased and, on occasion, guilty of ridiculously bad journalism. If you're a baseball fan, and you like statistics, I would highly recommend going to Fangraphs, if only to look around.
FanGraphs is a good resource overall, but their site can be buggy and doesn't always work as intended.
Baseball Prospectus lacks the depth you'll find on FanGraphs, but the site is more reliable.