so for tunetunnel I want to add a feature where users can pick songs and put them in *theirusername*.zip folder

Basically the user will click a thing saying *add to zip* which will call upon zip.php?file=http://www.site.com/file.mp3 which will add to an archive called $_SESSION[username].zip (so *theirusername*.zip) and they can download it by going to tunetunnel.com/archives/*username*.zip , and they can add and remove stuff from their little zip archive. And all the zipping will be done server side.

If someone could write me up something like this, i don't have much money to give out, but i will advertise something for you on my site or give you credit (or both).