Other
Lute Harpsichord: A Forgotten Instrument
Interesting website on the lute-harpsichord, which is called "one of Bach's favorite keyboard instruments." Provides an in-depth history of this "forgotten instrument" and the ordinary lute.
University of Michigan
University of Michigan: Instrument Encyclopedia: Baroque Organ
This lesson has brief info on the baroque organ and its history. You can also listen to a sound sample.