Like any other jQuery developers, I spend a large amount of time digging in the documentation. jQAPI is a website which provides the jQuery documentation in a more user-friendly way, so it is now my reference site when I need any jQuery help.
Respond.js is a small script that allow you to use CSS3 media queries on browsers that do not support it yet (Yes IE, we’re looking at you…).
Modernizr is a script that helps older browsers to work almost as good as newest ones, so you can build modern applications that will work on IE6 and 7. Your clients will love it, that’s guaranteed.
YepNope aim is pretty simple: It answers yep, or nope. For example, ask YepNope is Modernizr is loaded. If yes, ask YepNope to do this, and if not, ask YepNope to do that. That’s simple as that, and very useful in many cases.
Ligature.js is, unsurprisingly, a script that adds pretty ligatures to any kind of text. A must-have for all typography lovers out here!
FitText is a very interesting tool, that allows the automatic resizing of a text regarding the size of its parent element. Just have a look to the website and resize your browser: The text will fit. Another very interesting tool for modern websites and applications!