The free online service gives you a break down of the price for 15 North American and European cities. A simple query for a fare from the Chrylser Building to Penn Station shows the 3.14km ride to take about 9 minutes and cost $10.28. World Taximeter estimates the cost not only based on the distance, but the average wait time, any peak hour surcharges, and 15% tip.
Although the search helps you by suggesting famous landmarks, the service is a bit shoddy unless you use specific street addresses. Hopefully World Taximeter will expand its list of cities offered (they are currently taking suggestions).
Knowing how the approximate distance and fare for any cab ride when you travel around the world is the best way to avoid getting ripped off.