Muxtape was a site you may not have heard of, it wasn't exactly incrediably well known, despite having a quite large userbase. The site allowed you to upload mp3s into a mixtape of songs which you could then share with friends; but you could not search the site or discover other peoples "tapes" without the person giving you the link. Obviously the legalities were dubious, and it ended up with too much legal pressure to fight.

It's unfortunate, I didn't have a great deal of experience with what seemed like a great idea.

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