Ok, so I'm not bagginsbill, but thought I'd offer an opinion here.

To my mind, bruising is something better left to a texture map, rather than procedural node-work. Why? Well, because (haveing recently injured myself in a bike accident and got the evidence to back it up) bruising tends to happen in specific places, at the points of contact. For example, I've had a bruise on my left knee for a week and a half now wwith an unharmed area in the centre, based on something (I don't know what, exactly) which protected that section. Bruising can also take the shape of the specific object which left the mark - the assailant's fist, for example. Thse specific shapes and locations for the damage would, I think, prove beyond the capabilities of a node-based solution.

Of course, I now look forward to bagginsbill to come along and tell me I'm wrong... : :)

jonthecelt