GeoClass helps you to handle georeferenced data (latitude and longitude values for a location). It enables the connection to databases which provide these data or you can easily create your own GeoObjects.
If you know the location of two places you can search out the distance between these and the orientation from one location to the other.
One benefit of GeoClass.php is the support of RDF-files with georeferenced data as defined by the w3.org. A GeoObject can be coverted to a RDF-file and a RDF-file can be parsed an outputted as an array of GeoObjects.
There is an extra class to handle databases from NGA, National Geospatial-Intelligence Agency (formerly known as NIMA,National Imagery and Mapping Agency).
Arne Klempert improved GeoClass.php a lot. One new feature is the integration of the drawing of GeoObjects into maps. Last but not least GeoClass does the data-handling for OpenGeoDB.de.
Later this month examples will be released on OpenGeoDB.de.
Download the GeoClass beta package at sourceforge: http://sourceforge.net/projects/geoclassphp
Send any comments to my e-mail-address.