Rogue archivist Carl Malamud sez, "Public.Resource.Org today released a metric boatload of early federal case law (1880-1923), known as the First Series of the Federal Reporter. The Second and Third series were released earlier this year, as well as the "Federal Cases" which are the precursor the Federal Reporter. We're about 89% of the way towards a complete release of the Courts of Appeals archive."
Link to announcement, Link to archive
(Thanks, Carl!)
See also:
1.8 million pages of US federal case law to go online for free
Opening up the American lawbooks