I Feel Love, by Donna Summer -- in conjunction with the Italian producer/genius Giorgio Moroder.

The first real trance song. Hard to imagine most modern electronica without it.

Still an urgent, slinky, exciting tune today -- and it will be 30 years old this year.

Afterthought

I would also like to call it audio literature. Listen to it through headphones a few times; you can always pick out a few things that you didn't notice before -- and they will make you appreciate this amazing song all the more.

This Wikipedia post has a list of those who have either covered or borrowed heavily from the song.

This YouTube clip has a decent version.