"But I've been having a mid(i)-life crisis" - I Am With Name
MIDI is a sound format which uses wavetable and/or sampled instruments together with instructions (e.g.play a middle C for half a second) to generate a full instrumental version. There are a multitude of MIDI players for most personal computers. In particular, anyone with a recent version of Quicktime should be able to play these directly. RealNetworks also includes MIDI capability in their later players. For more information on MIDI, visit this Harmony Central page.
The following MIDI files were collated and sent in by various contributors. Jillian S. started it off with around 29, and Teresa S. added another six or so. If you have more, please feel free to send them in as well.