Shira - an American based site full of all sorts of information about belly dance.
http://www.shira.net/

A good site with information about pre and post natal belly dance classes.
http://www.bellydancer.org.uk/

For information about events and workshops
http://www.wiggle.org.uk/index.htm

For all of your costuming needs
http://www.forbiddenfruitsbazaar.com/