Disco singles! I have about 15 ultra rare extended-play "promotional copy" 12" 70's disco singles that I acquired from a discotheque in 1978. I like to play them to bring back memories and to enjoy the great dynamic range these discs have (many are 45 RPM). Here are a few:
Boogie Nights
Which Way is Up
Night Fever
Love Hangover
Dance Dance Dance
Miss You (Rolling Stones)
Groove Line
Shhhhh! Don't tell.