Here at music4dance.net we're busily cataloging music with a specific interest in what dance styles 'work' with the music. Since we come from a partner dancing background our system is set up primarily to work with traditional ballroom and partner social dancing like Swing, Salsa and Tango all of which are danced to music of a specific meter and tempo.
With the interest in shows like So You Think You Can Dance and Dancing With the Stars, styles like Broadway, Contemporary, Jazz and even Ballet and Tap have started to show up in the lists that we are adding to our database.
None of these style of dance operate under the same meter and tempo constraints that we are using, so we're creating initial place-holders for those styles and others that we'll roughly call 'performance' dances while we figure out how to generalize our website for such dance styles.
In the case of Hip-Hop, we haven't even added any songs to your catalog. If you are interested in helping by either providing a good description of Hip-Hop that we can use on the site or a list of songs that are great examples of music for dancing Hip-Hop, please contact us using our feedback page.