Leakage on driver side floorboard
 

I was cleaning out my car and noticed that my floor board was wet on my drivers side. I have no idea what could be leaking under the floor board, but it looks like coolant. Any ideas?

Most likely the rubber o-rings that frequently fail on the heater core. Check out instructions that I've seen on many sites on 'How To'

+1 on the heater core. While this didn't happen on my S80, I had a 960 with the same problem and the floorboards would always be moist. We ended up just bypassing the heater core as it was during the summer months when the issue was occuring.