Free GM Resource: GM Hold Music
Now I don't always play mood music when I run a game, but there is one particular sound file I try to keep handy, especially when I run a convention game. Going strong GMing a four-hour con isn't always possible and inevitably the group wants to take a 5-10' "breather" halfway through.
That is when I like to whip out this little gem and play it on my iPad: GM Hold Music by R. Dominelli. This MP3 is just over 5 minutes long and is usually entertaining enough that those players that don't get up to smoke or use the bathroom are entertained.
This is listed as "Volume 1". I've been searching for a Volume 2, but I have been unlucky so far. If I was funny enough I could see trying to make something myself, but I'm not that talented.....sorry guys.