New from the Ibuildings techPortal there's this article from Paul Matthews about using MongoDB in PHP applications. It's an introductory level tutorial that uses the MongoDB extension for PHP to interface with a local database.

This tutorial will show you how to incorporate MongoDB into new or existing object-oriented applications, by showing how to interact and integrate with applications and how to deploy applications using MongoDB. [...] If you’ve implemented MongoDB into many of your systems, then maybe this tutorial will, open your eyes on a new way of integrating it. Whatever your background, if you understand object-orientation and want to start using MongoDB, then this tutorial is for you.

He links you to the resources you'll need to get things set up - the extension and a MongoDB - as well as some "first steps" creating a sample Link and LinkPeer objects. There's code examples of how to pull in collections, insert data back into the database and update/delete too. You can grab the full source of his examples from his github account.