Asbestos siding, also known as cement asbestos siding or slate siding, isn't manufactured anymore and is only found on older homes. Though it's just finely ground asbestos particles mixed with cement, since it's mixed with the cement, it can't be breathed so isn't usually a health threat.
To make asbestos siding look better, apply a coat of latex paint. Minor cracks are not a problem, but if the siding is seriously damaged -- especially if it turns to a dust-like material -- it should be handled by a professional.
-- Tips courtesy of HomeAdvisor.com