Midis

Midis are commonly used in websites as background music or jukeboxes because of its small size compared to normal music files such as Mp3s or Wav.
They do not contain any vocals so you don't hear any words or whatever.
I have a midi file on this website if you look at the top right hand corner of the page you will see Play and Stop which is quite self explanatory... so yeah you can listen to the song which is on it, but shut down any other music you have on already!

Below are some links where you can download midis.
Note: clicking on the links will open a new window

Find Midis

Midi Database

Free Midis

Classical Midis

Ifni.com

Midi Karaoke

Gs Home

Music Robot

Some links may not work.