Present.me is a web service that lets you create effective presentations through your PowerPoint files.  What makes this site unique is that it lets you add a narrative to the presentation. Once you upload your PowerPoint, you can record a narrative through your webcam and microphone as if you were presenting the slideshow. The final presentation then appears with your webcam recording on the right and slides on the left. A filmstrip view of the slides is also given on the bottom of the presentation. 

This an example of the information provided to students for their graded oral examination. And this is a student example of a PresentMe presentation: