The PHPGeocache library is a newly released (version 1.0 on July 30th) toolkit to help any web developer work with geocaching quickly and easily on their own site.
More and more people are learning about the fun sport Geocaching. Why not integrate geocaching data into your own website, creating a mashup or simply creating your own geocaching website?
PHPGeocache is a free toolkit implemented in PHP which allows everyone to integrate geocaching information into his own website. And yes, it can also be used for commercial projects.
The library allows you to grab and store geocoded data in a local database and makes it easy to pull the information out and manipulate it as you need. There's also a built in system to create paths of wyapoints for a hunt in true geocaching fashion.