There's a dispatch office at the airport; you can also flag down taxis on the street (look for license plates with a "TX" tag). Rates are fixed (i.e., there are no meters; the rates are set by the government and displayed on a chart), though you and the driver should agree on the fare before your ride begins. Add $2 to the fare after midnight and $2 to $4 on Sunday and holidays. An hour-long island tour costs about $40, with up to four people. Rides into town from Eagle Beach run about $8; from Palm Beach, about $13.
Airport Taxi Dispatch (297/582-2116).