For the past week, I've had a problem with the clutch staying on the floor when I push it; I'd have to pull it back up manually for the first 10 or so uses when I'd first start the car. This weekend it stopped coming back up at all, so it wasn't just the cold. A quick check later, I was off to Pep Boys to pick up a bottle of Valvoline SynPower (DOT-3/DOT-4 brake fluid) to fill up the bone-dry resevoir. An hour of lying on my back in Chicago's fine February weather bleeding the clutch slave cylinder, and pedal pressure was nice and stiff again.
I also took the opportunity to pull the K&N filtercharger air filter off the car, and give it a thorough cleaning. A test drive afterwards showed a noticable seat-of-the-pants improvement (not surprising, given how much crud had built up on it since it's last cleaning), and demonstrated pretty clearly that my clutch is beginning to slip (a shift into 3rd at WOT resulted in the RPMs skyrocketing, but no speed increase). I'll have to address that in the spring.