I’ve been needing to lookup the geo-coordinates of a number of places lately, and couldn’t really find the perfect solution for what I needed; MapQuest is from 1995 and none seem to provide a bounding box. I have to say that the Yahoo Maps AJAX API is dead simple, and making my own only took a few minutes. Click the following picture to open the finder in a new window, then resize/drag/zoom to find your location:
Or, if you’re afraid that I’m making you change your popup preferences so that I’m IN UR BROWSER KILLIN UR D00DZ, you can also find the project here: https://overstated.net/projects/lat_lon. And the source.
overstated 
IM IN UR MAPS, BOUNDING ALL YER BOKZ
If you are looking for latitude and longitude data for your application, you can receive up-to-date geo data for N. American Zipcodes, along with latitude and longitude, county, and country information from http://www.meridianworlddata.com. You can also download complete geographical databases for cities, land features, water features, and man made features around the world. You can then use this data within your calculations to make sure you have the most up-to-date data.