GENERIC
http://www.superpages.com/ - the online Yellow Pages
http://theusaexplorer.com/ - a huge directory listing businesses by town and city
http://local.yahoo.com/ - city guide
http://phones.whitepages.com/ - the online White Pages
http://citysearch.com/ - city guide
http://www.yellowusa.com/
DANCE-SPECIFIC
http://dancestudiosusa.com/ - dance directory
http://www.getyourkidsoffthecouch.com/ - collection of kids activities
http://www.dancedirectory.com/ - ballroom dance directory
http://www.dancedirectoryplus.com/
You might also want to do some research and see if your city or town has its own online directory. My city has an online kid's directory that lists dance studios, gymnastics facilities, karate, etc. Also check your local newspaper, radio and TV station websites for business listings. If you offer birthday parties, there might be an online directory for kids parties - make sure your studio is on the list!
Also, many of these are specific to the United States - for other countries, you might need to do a bit of googling to find directories specific to your country.
Anything others you can think of?
