Over the holidays, one of the users of Plan-B for OpenOffice.org asked me “Is there something equivalent to Powerpoint [Viewer]?” so you do not need to own the software to receive and view ODF files.
To the best of my knowledge there is not. Actually I would think there is not need. As anybody can download Open Office for free and install the full package it is about as much work as downloading the free MS Office PowerPoint Viewer.
One could argue that this is not equivalent, because you want to only install the viewer for presentations and not the whole application. However you can install only Impress the Open Office application for presentations and the difference in file size is minimal. You even get as a goody the presenter mode, allowing you to not only view the presentation but also present it on an external monitor. Free open source has its benefits I guess.