A while ago Adobe released Adobe AIR. AIR was a way of running web applications on your desktop, even when you don't have an internet connection... The problem was, that never really worked... Worse, AIR was not open-source...Finally, it looks like the right thing has come along: Appcelerator Titanium. Appcelerator Titanium claims to be "the first open platform for building rich desktop applications." Basically it lets you write desktop applications in HTML, CSS, and JavaScript, just as if you were writing a web application. Like Adobe AIR, though, you don't need an internet connection to run Titanium applications.