Hi everyone,
I read a horror story in the TNT magazine (UK) about dodgy taxi drivers ripping holidaymakers off at Fiumicino (Rome) airport - even off people being forced to pay up to �100 for a �10 trip.  I did some hunting on the net and found a really good website www.thingstodo-rome.com - the website has a section under transfers where you can book a cab online for $16.17 (USD) - you get a confirmation voucher and your car is guaranteed.  There are some catches e.g. it is a shared taxi & your hotel has to be within a certain area (they are all listed so you can check) but at least it is legit & you don't have to worry about being harrassed at the airport.  I hope this is helpful - good luck!
Ciao Michelle.