Short bio: Computer Scientist, FOSS supporter (read more)
Tux Machines (TM)-specific
One of my biggest concerns when I adopted the Linux OS over Microsoft Windows was Linux's ability to supply me with a robust presentation program. I did lots of lecturing and instructional seminars. Those activities required a product that closely mimicked Microsoft PowerPoint quality. The resulting file also had to be compatible with PowerPoint.
My first foray into a replacement for the Microsoft Office suite of which PowerPoint is an industry staple was the close look-alike bundle from OpenOffice.org. Its presentation module, called "Impress," did a great job of doing exactly that -- impressing me.
Impress let me work much the same as if I were still using PowerPoint. It botched some of the display elements when viewed in PowerPoint, however. But if I avoided the really fancy stuff in my slide designs, I got few complaints from colleagues who imported the Impress presentations in Windows.
Two other Linux apps give you different options for working with presentations. An alternative to OpenOffice's clone app of PowerPoint is the module bundled in the KDE Project. KPresenter is a full-featured app with fewer bells and whistles.