In the "What now?" department...
I drove my yellow car to work, enjoying the cool AC. All was fine -- got to work, parked the car, and went in.
Then a fellow employee came in and told me that there was steam rising from my car, and a pool of coolant under it. I went out and found the hose going from the thermostat housing down to the coolant tube popped open. The car didn't over-heat going to work, so I guess it's just the 22-or-so year-old hose giving out. I don't think anyone makes that hose anymore, so I'll have to go to the parts store with the old hose and see what I can find.