The above mp3 file is an audio collage of 20 rather short clips from unidentified cover songs, most of them fairly recent. The challenge was to name each song, the artist performing this version, and the artist responsible for the original version. All tactics were permissible. Some of the songs and performers are fairly well-known, some are not. The clips are in alphabetical order by original author, although in a couple cases "original author" is a little ambiguous, and I accepted any defensible answer.