Someone combined Google Maps with the DC taxi zones system, so you don’t have to rely on that 99% blank map in the cab’s back seat to know whether or not you’re getting ripped off:
Courtesy of DCist: Go, Go, Google D.C. Taxi Maps
Or you can use the government version that looks like it was made in 1995.
Or they could just switch to timed meters. I don’t understand how they live off of the $8 they receive for 45 minutes in traffic.