One of my players is playing an evil alchemist, and wants to use people as test subjects for his poisons. I offered to come up with a mechanical benefit to doing so, so he's not just poisoning people for the hell of it. I like the suggestion offered in this thread, allowing people to improve the DC of their poisons to a point dependent on their ranks in Craft. I'm thinking of adding the requirement of one "test subject" per DC (but you only need to do this once for each type of poison).
What do you guys think? Has anyone else done something like this?