Midi songs are ones that have been produced using an electronic keyboard. They don't sound anywhere near MP3 or CD quality, but for an average size of 30k, they sound pretty good on a wavetable sound card. They're usually used for kareoke.
I probably won't be updating this section any time soon, as I'm more interested in MP3, but I'll leave these up for anyone who wants them.

December 8 - This section is basically dead, so don't expect to see and new updated information in the future