While lazily browsing on the web, in found a very interesting UI created by IBM called the Glass Engine. The Glass Engine is used on Philip Glass website to navigate through the author's pieces library. The Glass Engine seems to have been created by IBM Research multimedia labs. Anyway, here is what it looks like:
Each horizontal bar is linked to an attribute of the pieces. For instance, the Work Year bar, highlighted on the screenshot, let you select pieces by year. Things get really interesting when you discover that all the bars are linked together. It makes searches quite easy to perform, particularily if you have no idea of what you're looking for. The five last attributes are particularily cool since you can use them to find a music piece by its mood. You want a joyful piece? Do you prefer a very slow one?
Give it a try, you might like it too :)