Although rarely used, an inventor can apply for a statutory invention registration with the patent office under 35 U.S.C. 157. Under the law, the inventor must waive the right to receive a patent on the invention. The statutory inventions are searchable through the USPTO patent database and are given “H-numbers”—such as H342.
There are currently just over 2100 published SIRs, most of which were filed by the U.S. government. This search (SEARCH) will grab them all.
(NOTE — This tip comes from the PUIG newsgroup).