Again letting someone else do the describing and listing:
There are a lot to choose from, whether for 50 $US or for 500 $US, with varying features of course. The features I was looking for were simple conversion of a powerpoint presentation that retains the narration already created in powerpoint.
A simple test with iMediaConvert‘s trial version shows that it provides additional navigation for the slides (list of slides plus simple play buttons), and does retain narration recorded with a Powerpoint presentation. The test file was not large, nor did it have transitions, so those would need to be further tested. From the results so far, though, iMediaCapture would be worth looking at more closely.
The same test with Flash Point, about the same price as iMediaConvert at 49 $US, produced a less than satisfactory result: the sound came through the conversion, but did not play back cleanly when navigating from one slide to another (sounds didn’t stop, so more than one slide’s sound playing at the same time). The default navigation was not functional (the slider was stuck in one position) and not all graphics cames through completely (standard diagram from powerpoint’s collection). This tool doesn’t seem quite mature.