USNO PMM Star Catalogs
nofs.navy.milUSNO is making the USNO-SA2.0 catalog (54,787,624 stars in all on one CD-ROM) available for free. The full USNO-A2.0 catalog (526,230,881 stars on 10 CD-ROMs) is also available provided you can provide a brief explanation of why USNO-SA2.0 is not sufficient. That's information on over half a billion stars!