Rich over at God and Science has a nice post entitled Does God Approve of Slavery According to the Bible?  I have not delved into this topic much, but I do like this one bit:

In fact, the slavery described in the Old Testament was quite different from the kind of slavery we think of today – in which people are captured and sold as slaves. According to Old Testament law, anyone caught selling another person into slavery was to be executed:

"He who kidnaps a man, whether he sells him or he is found in his possession, shall surely be put to death." (Exodus 21:16)