'03-'03.5 Mazdaspeed Protege. Cheap, reliable, good on gas, and a hoot to drive. One of the most entertaining front drivers I've ever driven, on the road or on the track. It handles well, comes standard with ABS (for those nasty, rainy commutes like we've had this week), a limited-slip front diff, and the mother of all AM/FM/CD/MP3 players. Has four doors and human-sized back seats, so it fits the practical side as well.
You can pick them up all day long for well under $15k with minimal mileage.