Took the car into the shop tonight. They found the cause of that metal-on-metal noise I was hearing. The cala-something, the thing that controls the brake pads' movement against the round, flat, metal thing, wasn't working right, and so the brake pad was 100% gone and so when I applied the brake it was, in fact, metal on metal. (Hello run-on sentence!) The cala-whatever needs to be replaced, and of course it needs new pads. That's about $500. Plus they found some, um, something else that needs replacement, too. The serpentine... cord? Wire? Something, it needs replacement as well. Nearly $100.
$500 + $100 + $20 (for the original oil change), plus I left work a little early tonight and I have to arrive two hours late (without even notice!) tomorrow.
Plus in the next 5,000 miles or so it will need new tires.