http://memory.loc.gov/ammem/dihtml/divideos.html
It has about 75 short video clips of ballroom dances from the Renaissance through the 20th century, with close-up step demonstrations as well.
I also came upon a new book at the library, The Dances of Shakespeare by Jim Hoskins. This is an illustrated guide to all the dances mentioned in Shakespeare's plays, as well as brief descriptions of later ballroom dances for those stage directors who want to set Shakespeare in a different time period. Among other things, I learned from this book that "God Save The Queen/My Country 'Tis Of Thee" is a dance melody. You can waltz to it, as you can do with the vast majority of triple-time tunes, but it is properly a tune for a galliard.
