Back in the stone age, one of the more interesting classes I took was Behavioral Medicine- this was in the 80's, when the whole biofeedback thing really actually gained a bit of legitimacy. Since you already have skin resistance and there plenty more inputs, maybe youcould add in more sensors..
Oxygen saturation is a good one, sat can drop due to anxiety.. And with the same detector (IR pair on fingertip works I understand) you can determine heart rate and respiration rate. If you've been in an ER recently, they put one of these on you. Work great and non invasive. A few searches should yield some info on how to implement.
THEN, you can implement session data storage and upload to PC via serial, where the data can be graphed and trended...
Products like these, though relatively simple, really do work well and can even help change things for you, medically, in the long run!