Administrative Office of the Courts. Reports and data tables from the US Courts. Statistics on caseloads, complaints against judges, multidistrict litigation, judicial vacancies, disposition times, types of cases. These are available as pdfs or as data tables.
National Center for the Courts/Court Statistics Project. State court statistics, including caseloads by type of case.
Proquest Statistical. Statistical reports related to various court systems, including the Federal Court management Statistics.