Every song for every USA Billboard year-end top singles chart from 1946-2012.

6,102 total songs.

1946: Top 48
1947: Top 47
1948: Top 39
1949-1955: Top 30
1956-2012: Top 100 (more than 100 for some years due to multi-song singles)

Each year is in its own uncompressed ZIP archive (with a directory for the year inside).  I would have uploaded the loose files, but The Pirate Bay's interface couldn't accept it with that many files, even when I split the collection in half.

Every file is consistently tagged and has ReplayGain information set.  All tag information comes from the chart data at http://www.bobborst.com/popculture/top-100-songs-of-the-year/ and should match exactly.

Everything is in MP3 format, and the vast majority of the songs are good quality, although about 200 or so songs from the late 1950s are at 96kbps.  Originally, most of these came out of other torrents on Demonoid, so it's what there was to work with.