This is really exciting to me. Andy Clark has developed a graph, based on some original work by Colby Cash, that displays the basic pitching prowess of all qualified major league pitchers (strikeout, walk and home run rates). You can look up all qualified pitchers in the history of a franchise, or all qualified pitchers in a single year.
Some of the theory behind this graph can be read in a Baseball Graphs article. The basic idea is that being in the upper right is good, the lower left is bad, and big circle sizes are good. You’ll need the latest version of Flash to use the graph, but it’s worth it.