280 Slides is a web-based Javascript clone of Keynote. I loved the style and this is how simple I want web editors to be. Microsoft, you should take some ideas from here to Office Online.
The most amazing thing about this is happening under the hood: the developer wrote a library that abstracts browser rendering engines using Canvas, SVG and Flash (on a per-need basis) into a unified language – Objective J which is – as the name suggests – a mapping from Objective C to JavaScript.
Source: Wait till I come!