Longitude & Latitude to Miles/Kilometers

My Google-fu is failing me.

Is there some resource on the web that converts Longitude & Latitude coordinates into distance in miles/kilometers? As in “W39.58785 N38.44568 is X miles and Y kilometers from E11.77889 S44.55859”?

This is natively supported in the Google Maps API. Not sure if that really helps you though.

Calculator: http://www.nhc.noaa.gov/gccalc.shtml
And the ‘more info link’: http://williams.best.vwh.net/avform.htm

I like the Great Circle Mapper. It both calculates the distance and displays the result on a map. It accepts input in both lat/long and IATA/ICAO airport identifiers.

Wolfram Alpha has this as one of the built in functions:

http://www.wolframalpha.com/examples/GeodesyAndNavigation.html

I keep WA calculator on my iGoogle start page.