I've been looking at Fairfax Collegiate (day programs) but I haven't been able to find much feedback on them.
The University of Maryland offers some science/engineering camps and while they haven't yet updated their page for the coming summer, you can see what they offered last year here...
http://mrsec.umd.edu/Education/PreCollege/Summer/GMU also offers a variety of summer camps. They are finally starting to update the page, but the downside is it is basically empty right now. It will be here...
http://summercamps.gmu.edu/#Academic
