I downloaded Fliggerty's mod yesterday. It's perfect for what I was looking for, which was to be able to do something with all the slaves you find in smugglers caves and such. If you have their key, instead of just being able to free or leave them, you can force them to your own service. From there, you can lug them around as companions, packmules or sell them for a very tidy profit at slave dealers. I thought it was kind of neat. It just introduces basic game mechanics though - the slaves themselves don't have any real personality. Check it out and see if it's too your liking.
http://planetelderscrolls.gamespy.com/View.php?view=Mods.Detail&id=5630.