Flexable Rapid Application Development Idea

For some time I was wondering if there was an environment which combines the best of XHTML and Python. With XHTML information, forms, media, etc. could be very quickly and easily be constructed and modified with very little effort. JavaScript, however, is very limited in its functionality. One cannot write a web page that can launch programs or open files from one’s hard drive for example. Python has a ton of great functionality.

I came up with this thought while I was trying to make a super work-centric homepage for Firefox to load on startup. I realized that I could not have links to my most frequently used applications and files, which would have been nice. I implemented some of what I originally wanted in JavaScript (a simple daily schedule, a clock, favorite links, etc), but I could not create a flexible and expandable command center with everything I need organized together right in front of me.

Is there already rapid application development environment like this? If there isn’t, do you think this would be a good idea? It is not a web browser, but it could have all of the functionality of a web browser plus so much more.