I really thought I had this car figured out...

There's a coolant leak. All the hoses are dry (Upper, Lower, and Heater). No apparent leaks coming from the thermostat housing (just replaced gasket) or the radiator itself.

However, underneath the lower wheel of the timing belt (closer to the driver) there is coolant pooling on a little plastic piece. I've uploaded a photo. You can see on the right 2 little green dots of anti-freeze dripping.

Are we talking water pump/timing belt change?

 

That looks like a water pump leak to me. Mine did the same thing from the same place and I ended up doing the timing belt ,water pump and tensioner change. Look at it this way,its probably about time to change the timing belt anyway.