PZ Myers comments that Huygens and Cassini make for a pretty hot topic right now. So you may be getting biographies soon, but for now, just some links.
Christiaan Huygens
Giovanni Cassini
The Galileo Project
The scientific revolution
The Plurality of Worlds
Mathematicians of the 17th and 18th centuries
Early modern women in Science
Women philosophers of the 17th and 18th centuries
History of mathematics
The MacTutor history of mathematics archive
Seventeenth-century astronomy
Update: you might also want to read this review of a new book about Robert Hooke, which just turned up in my mail. (And this slightly older one.)