Lily

www.lilyapp.org

Lily is a Firefox add-on that allows users to create rich, complex applications in a web browser. With Lily it's possible to make programs that mashup the web or the desktop, visualize and animate data, modify webpages, play music, or connect to world outside the computer. Lily programs can be shared with other Lily users as text files or run by anyone as Firefox add-ons or standalone XULrunner applications. Lily runs on Mac, Windows or Linux, just like Firefox.