280 Slides is an interesting application, not so much because of what it does, but because of how it does it. It’s a nicely made presentation tool, but pretty basic as far as these things go (no animations or transitions, for example). But the whole thing runs in your browser, with no Flash, and has a nice snappy feel. The most startling thing though, is the language it is written in: something called Objective-J, an Objective-C clone implemented in 13Kb of JavaScript, executing in the browser.