Music Explorer is a Nokia Developer example application demonstrating the use of Nokia Music API together with standard Windows Phone 8 audio features. Not only is it a well run project, but as of March you can download the app from the Windows Phone Store and try it out.
The project shows how to use the Nokia Music API to search for artists by name, request top artists and new releases, and it also shows how to launch Nokia Music application from within another application to play mix radio or show artist and product information.
Besides utilizing Nokia Music API features, the app integrates with the local music in the device in a number of educated ways. Favourites are ordered according to the most played artist in the device, recommended list is ordered by how many times an artist is found to be similar to your favourites, and you can also play the local songs of your favourite artist.

The project is well documented in its wiki. As will any Nokia Developer project you can raise defects or enhancement requests within the project itself or simply discuss it with the project team.
Music Explorer is essential viewing for anyone who wants to work with the Nokia Music API on Windows Phone.
– Hamish Willee (on behalf of the Projects Moderation team)