Argumentative lets users create "argument maps," visual displays of the reasoning involved in creating a good argument. It's great for students studying persuasive writing, logic, debate, speech, social studies, and any subject that requires essay writing.
Prezi is a web-based presentation application and storytelling tool that uses a single canvas instead of traditional slides. Text, images, videos and other presentation objects are placed on the infinite canvas and grouped together in frames. The canvas allows users to create non-linear presentations, where users can zoom in and out of a visual map.
A VoiceThread is a collaborative, multimedia slide show that holds images, documents, and videos and allows people to navigate slides and leave comments in 5 ways - using voice (with a mic or telephone), text, audio file, or video (via a webcam).