"Pretrial Release of Felony Defendants in State Courts":

A very interesting new report from the U.S. Department of Justice, though limited to the top 75 largest counties (and covering 1990-2004).

An example of the kind of data you can find: When the most serious arrest charge was murder, 45% were denied bail, and 35% were required to provide bail of $50,000 or more; 19% were actually released. For the next most serious charge, rape, 9% were denied bail, and 25% were required to provide bail of $50,000 or more; 53% were actually released. There's much more interesting material in that report, and in the supporting data files.