New ICPSR data releases here. One that caught my eye is the 2004 update for the National Judicial Reporting Program Series. Although the 2004 sample is a cross-section, the series enables longitudinal analysis from 1986 to 2004. Here is a description for the 2004 dataset:
This data collection provides detailed information on the sentences and characteristics of convicted felons based on data collected from state courts. The 2004 survey was based on a sample of 300 counties selected to be nationally representative. The collection contains sociodemographic information such as age, race, and sex of the felon. Types of offenses committed include homicide, rape, and robbery. Data can be analyzed at the national level or by individual counties.
There is a lot of county-level demographic data available from the Census Bureau, including shape files for GIS mapping software. All of these data sources can be linked together in a matter of hours thanks to Census Bureau FIPS codes. For a criminal law scholar interested in empirical research, this is great (and free) starter data set.