Freestyle is a great way to polish heeling and create a fun exercise for you and your dog, whether you intend to compete or just do it for fun.  If you are good at it, you can always offer to demo your routine for Club functions.  Its often called "dancing with your dog".  Several organizations hold competitions and demos.  Read each organizations rules and decide where you fit in.

Organizations

World Canine Freestyle Organization   This organization has
video competition, as well as fun meets and competitions all across the
country. 

Canine Freestyle Federation  - CFF -  geared more to polished heeling
and lots of it, showing the beautiful relationship between the dog and
handler, and less on show business. 

World Canine Freestyle Organization - WCFO   many different divisions to
compete in.  Some more geared for the "entertainer" with props allowed and
costuming;  and another heelwork to music is showing polished heeling
with other moves. 

Musical Dog Sport Association - New - all levels and newbies welcome
 

Other Resource Sites for Musical Freestyle

 Jill Fenando - She dances with ACDs!

Another good site - nice streaming videos

Sandra Davis - Dancing with your dog (instructional videos to order)