This is part of a web site I've been working on. You can use it to compose a song online and send it to your friends, like this:

http://www.plernpiano.com/share_landing.php

That's an example of a widget that plays a random song, but you can also have it play a particular song you've composed. You can also browse all the songs that others have entered into the database.

You can compose songs here: http://www.plernpiano.com

Check it out and let me know what you think. Thanks!