have a look at the app here:

Features and Problems

• works on facebook and on any other webpage
• enables setting more and more songs free for streaming while more people install the app (in order to spread the word)
• users need to connect (with facebook or via email adress) in order to listen
• some lightweight statistics
• encrypted flash player (not open source yet) that makes it hard to download the music (Though I myself have some moral problems with this kind of feature. But well it is how the industry works…)
• Slideshow of pictures to improve listening experience
• optimized usability for high conversion rates

The app runs on PHP, MySQL, JavaScript (MooTools) and you will need your own webspace in order to host it

A kind warning

The App was developed with a lot of time pressure and we had some nasty bugs that needed to be fixed. That is why the source code is messed up with some really fast and dirty quick fixes. Afterwards I never really had the time to clean up the source and make a good documentation. As my PhD progresses this situation will not change in the foreseeable future. Since my prediction says that Facebook will be overrun by Google+ within this year it is more than time to share the app!
The good part: most of the stuff can be reused once Google+ opens its API and the app can be transformed to a great social network.

Source code on google code

http://code.google.com/p/in-legend-facebook-music-streaming-app/source/checkout