Ability to have the "slideshow" mode record a video to disk (.mpg or similar). From the online slideshow (manually controlling the advance) or as a batch mode conversion.
Powerpoint can do this (Libroffice cannot), specialist software like photostage can do this (with more control on movement between images) but sometimes a quick video slideshow (without providing access to the underlying images) is all that is needed for sharing.
Powerpoint can do this (Libroffice cannot), specialist software like photostage can do this (with more control on movement between images) but sometimes a quick video slideshow (without providing access to the underlying images) is all that is needed for sharing.