Andros on Ballet is a wonderful resource for dancers and teachers alike. The author, Dick Andros has been involved with dance for over 50 years and he has a wealth of experience to share with readers. Here you will find pieces on history, vocabulary and an extensive biography area that features dancers such as Cynthia Gregory and Anna Pavlova.
(Just a little warning–you could spend a lot of time browsing on this site, so you may want to save it for when you have a little bit of time to sift through all of the information that is there.)
This site was a great find! I stumbled across it when doing a bit of research for my Origins of Ballet post. Another helpful ballet history site I came across recently is all about the Ballets Russes – http://www.russianballethistory.com/
Thanks for sharing the site–and for the comment Nichelle!