Since you say it's red, I believe it's the low brake fluid indicator. Had you said yellow, I would've thought it was the brake pad wear indicator. Red rules out windshield washer level, the aforementioned brake pad wear indicator, engine oil level, coolant level, exterior lamp failure, ABS, ASR and 4matic (if your car is so equipped). The only other red indicator lamps are battery, parking brake, SRS and Check Engine (if you have that feature).
Hope that somehow helps...