A Roman slave wasn't much like what we think of as slaves now (i.e. blacks on cotton plantations). Epictetus, for example, was a slave, and who even remembers now who "owned" him?
There were many black artisans in urban areas of the antebellum south who were slaves in just the way that Roman slaves were, doing highly skilled work without personal freedom.
Epictetus is, uhhh, an extremely atypical example of Roman slaves. Most of them weren't kept as pet philosophers.
Most of 'em were working in the fields, most of the rest were serving in their masters' houses, and the majority of the rest were probably doing far worse things (working in the mines or dying as gladiators).
http://www.amazon.com/Artisan-Workers-Upper-South-Petersburg...