IClickr lite is a free version with limitations of the maximum number of PowerPoint slides per presentation and without the facility to show presenter’s notes etc. Works best when run over a wireless network and only requires the two devices be connected to the same wireless network. To install, download the application to your computer and then install the iClickr application for your phone (iPhone, Android etc).
This application runs both on Windows and Apple computers and is easy to install. If you are looking for a solution to control the PowerPoint presentation on your computer from an external device, consider installing iClickr.