A relative occasionally makes PowerPoint presentations when she travels, but she is looking for a capability that I don't think it has.
When she displays a slide of a complex flowchart, she wants to be able to move around it at random, zooming in on various areas or pathways to make them visible. This would be in answer to questions from the audience, so she cannot predict in advance what needs to be enlarged.
Prezi lets you zoom in on areas, but I think you have to program the areas in advance. (I may be mistaken about this.)