The HTML5 Shiv : The HTML5 Shiv enables use of HTML5 sectioning elements in legacy Internet Explorer and provides basic HTML5 styling for Internet Explorer 6-9, Safari...
hunt : Library to detect when DOM elements become visible and disappear on scroll.
stream.js : stream.js is a tiny stand-alone Javascript library that unlocks a new data structure for you: streams.
jQuery : The Write Less, Do More, JavaScript Library
Add Clippy or his friends to any website for instant nostalgia.