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.
Chickenfoot is a tool that puts a programming environment in Firefox so you can write scripts to manipulate web pages and automate web browsing. In Chickenfoot, scripts are written in a superset of Javascript that includes special functions specific to we
These bookmarklets let you see how a web page is coded without digging through the source, debug problems in web pages quickly, and experiment with CSS or JS without editing the actual page.