Erm, I personally was leaning towards the captive/freedom area, not the slave/no chance of freedom thing, as I am loath to introduce slavery into a game.
I agree with the followers idea, however. If a captive has served his/her/it captivity and has the option to either continue serving you or go free, and chooses the former option, then you have a new follower. Followers are to be limited, like captifves, and can be turned against you. Not easily, though. The race of the follower will affect many things, as I don\'t think a creture of darkness would consent to serve a follower of Light. Then again, I don\'t know why the latter tried to capture the former in teh first place. Anyway, followers gain advantages, both in combat and civil affairs.
EDIT: Incredible amounts of new people in the forum... Their ideas would be interesting to read. Also, perhaps there could be people who pay for things with labor... After serving for a while, they are freed. If the \"master\" does not allow it, then interesting things shall happen... What those things are I\'ll leave up to you.