A keygen song is that music played in key generators, trainers, cracks, intros etc. They are usually chiptunes, but they are converted to mp3 for this site, because currently available web MOD / XM / IT players are not good enough.
Every song has been converted to mp3's also because they are just that much easier to use. You can download any song and play it directly without the need for any external plug-ins to your media player.
If you want the original files, most of the material comes from Keygenmusic.net . You can download them there in their original form. Keygenmusic.net has done a great labour in ripping that music from the keygens, and while we are not officially connected in any way, we do endorse them. Give their site a visit!
The site will get updates in time. Planned stuff include individual playlist functionality. But remember, this is a pet project, so they will arrive when they will. Enjoy your stay!