Fangraphs

I ran across this site a while back: www.fangraphs.com. I recommend checking it out. Here's a little blurb about what they do:

At Fangraphs we have 17 graphs for every player that played in the Major Leagues since 2002. That comes to about 30,000 baseball graphs. Every graph is updated every single day of the season with the most current stats. Not only do we graph ordinary stats such as batting average but we also provide graphs of various sabermetrics.