Presentations and Slideshows
Knovio - create and share online presentations with video and audio commentary
PhotoPeach - create online slideshows. Allows background music
Present.me - add a split-screen webcam recording to an existing PowerPoint, prezi, google doc or pdf
Prezi - online presentations with a zoomable canvas
VoiceThread - add voice comments from multiple users to a single presentation.
Zentation - allows you to sync a presentation to a YouTube video in a very unique way
Powtoon - make great looking animated videos and presentations