Ockham issued a great python script for changing settings of multiple lights all at once. Do a search for "ockham" in the free stuff and get "Python: Change lights, P5 and P4". This gives you a panel where all the ligths parameters can be altered (min shadow bias for instance), and the alteration can be spread to all the lights in a single click (check the "apply to all lights" radio button). As I like to use complex lightings, I use it a lot. Hope this helps.