If you are looking for an application geared toward managing extensive music collections, easy to use and with a comprehensive feature set - MusicBee is that application. MusicBee makes it easy to organize, find and play music files on your computer, on portable devices and on the web.
The screenshot above is Shane's spillpost. When you load any web page, a list of song files on the page is generated and you can listen to them as you read, download and/or add them to your library - all at the same time. There's also a lyrics/song info box. You can see the whole width of the web page - I just collapsed it in a bit for the photo size