I am currently in SFO (but not at the Kiva DO... a previously booked family trip), Just tried out a new car service called Uber. You can download the app to your iphone, set up an account, You can look a Lincoln Town Car online (they have a map showing where available cars are at -- when you book them you can track their progress on your iphone). They bill you direct to your credit card. Fare seems to be 50% more than cabs (but they have a $65 flat rate to SFO from anywhere in the city -- includes tip). Really great experience... Nice car... Great driver.... Understand they in some other cities also.