From my previous post I found “Miserlou” played by the Air Force. I managed to find some others that are pretty interesting. Some for the Christmas season, some patriotic songs, and a few hymns and ceremonials. Usually everything produced by the government is public domain, but things become tricky if they borrowed or used copyright or published material. The liner notes mention permissions from Warner Brothers, BMI, ASCAP, and other companies. It also states the CD is approved for use in public service broadcasting and Air Force activities such as recruiting, troop morale, and retention. They are certainly free, but there may be some restrictions I am not aware of (Like selling them would be illegal, not sure about filesharing).
The United States Air Force has kindly offered some mp3s from physical releases they’ve made. The link divides things into Patriotic, Ceremonial, Marches, Popular & Show Songs, Rock / Pop / Country / R&B, Holiday, Choral, Classical, Jazz, and Traditional / Celtic / Folk.
There are a total of 41 browsable selections.
Clicking “Next” will send you to the next album of theirs. Almost all releases have a few downloadable goodies. They all have mandatory preview as they start playing before you get a chance to download them.