My 1999 camaro has an annoying squeek coming from my rear passenger side spring. Is there anything I can do for it short of replacing the spring? I was hoping there is some kind of spray or something.

Are you sure its the spring? If so, I think you could apply some grease to the spring ends where they meet the spring perches. I know a lot of 4th gen camaros have squeaky sway bar bushings. I would try to grease the sway bar bushings and see if it goes away. My 96 had a similar problem within the first 5000 miles.

DenRS is right. It is most likely your rear sway bar bushing. I have a 2001 SS and complained about this squeak to the dealer. They put grease on the rear sway bar bushing and that took care of the problem.