A killer app is an app that makes a library or framework popular I think web.py is quite famous, But I do not know any large, widely used app written in the webpage. Can you tell anyone? I've headline that the first version of youtube.com was coded using web.py, but I want you to mention an open source so that I can see its code.
Here the list of "real web apps" is written in web.py from the website.
: A blogging and podcasting system : A Flickr powered photo gallery (v5): Play with colors A site for todo: A simple webpage example where you can create, delete and edit-in-place : A simple web app for music sharing (MP3 files). : An iGoogle gadget directory written in MVC style. : A very simple mass mailer. : A system for rating, commenting, and accepting candidates for the conference and choice. : Create randomly generated queries generated using Wikipedia.