try these:
wikifonia.comwikifonia.com RIP. they were unable to extend their licence.
[Musescore.com](http://www.musescore.com/sheetmusic "Makers of open the free open source WYSIWYG score editor "Musescore""): thisthe community site of the free open source WYSIWYG score editor "Musescore" has overa decent selection -over 10,000 pieces-, and they are all available inas a Musescore format file (meaning you can edit every tiny bit of the score to your liking), besides for .PDF, .Xml, .Midi and usually a .Mp3 format.