It is amazing to see the art of the rich internet application (RIA) rocketing ahead over the past year or so, after a slow and troubled gestation over the past 12 years or so. Much of the progress has been incremental and focused on technical reimplementation of old non-web concepts (think event handling in a form GUI). Sometimes we take a big leap forward (think rails, prototype).
37signals arguably kicked of the current phase of web applications with basecamp that finally allow us to forget we are working in a browser (or was it writely? - now google docs).
Now we are seeing a selection of frameworks or products specifically designed for building modern RIAs. Rails is of course now fairly established in this space, but products like Flex, Air, Appcelerator and WaveMaker are redefining the envelope.
Well I'll be bold enough to say now that I think the guys from 280North have just redefined the cutting edge again with their powerpoint/keynote killer called 280Slides.
It's just out in public beta (isn't everything?), but I challenge you not to be impressed with just how much like a great piece of desktop software it is ... except you've also got the power of web access, sharing and delivery.