A free app for Mac, by Autodesk
It's designed for teams working together who need to edit and access the presentations either separately or at the same time. The most useful aspect of this is an easy to read timeline that allows users to add comments regarding each slide and slice of text until it's perfected to everyone's liking. The final result can be exported as Sophie multimedia book (meaning your recipient will need Sophie installed) or as a PDF file.
The standout feature of this program however is the multimedia additions that are possible. You can add audio and video clips of any size to your presentations although the Sophie server can mean that working with them can be slow. Undoubtedly however, adding video and audio gives your presentations a touch of class that differentiates them from your average PowerPoint presentation.
Sophie is an excellent presentation creation program that brings teams together, adds multimedia, and it doesn't cost a cent.