Mobile phones have reached a level where it is possible to run selfcontained Augmented Reality applications using the built-in camera for optical tracking. In this paper we present some of our work in this area. We have created a custom port of the ARToolKit library to the Symbian mobile phone operating system and then developed sample applications which have been evaluated. These include a face-to-face collaborative AR game where we conducted a user study to evaluate multi-modal feedback. We also examined user interface issues where an AR enabled mobile phone acts as an interaction device. Additionally; we discuss how traditional 3D manipulation techniques apply to this new platform. We also describe a mobile phone based Augmented Reality application for 3D scene assembly; which adds a 6 DOF isomorphic interaction technique for manipulating 3D content.