Incompetech provides users with royalty-free music that they can use in just about any way they wish as long as provide attribution to the site.  One of most dynamic aspects of the search page is the ability to search for music based on Feel.  This allows you to search for music that fits the mood of your project. I have had students use this site to find music pieces to be their soundtracks to presentations about novels they have read.  They are able to find music appropriate to the mood of the novel.