Simple Presentation, Annotation and Whiteboarding Presentation Tool: PDF Presenter | Presentation Tools |

Robin Good: PDF Presenter is an open-source free cross-platform presentation software which allows you to edit and annotate existing content, import images and draw annotations .

With PDF Presenter you can type text next or over existing content, create multiple tabs with different whiteboards, and save your final work as a PDF file.

System requirements:
Java version 6 or higher.

Works on PC, Mac and Linux.

Free to use.

More info and download it here: 

(Thanks to Baiba Svenca for uncovering it)