Websites value regular users, but the problem is, you might forget they are there as there are too many to count. Worse, when you are travelling / offline, you can't get to them. If only they could put a mini application (yes, the application is still alive) on your desktop, you'd be able to do some useful things while not connected, and the sites' brand image would always be in your face.
Welcome to Adobe AIR
That's what Air does: it enables websites to break out of the browser. These applets don't have the full power of a traditional desktop application, but Adobe reckons they are much quicker and easier to write. Also, web developers create them using the tools with which they are already familiar, which is interesting. These include both HTML (JavaScript, CSS, XML) and Adobe Flash (ActionScript, Flex, XML). The Flash support means Air can also run audio and video.
