Unverse

In just 5k, Unverse has functions for lightbox (pop-ups for images, divs and web pages), drag and drop, Ajax calls, as well as displaying, hiding or positioning HTML elements. It implements DOM Ready: start executing your javascript without waiting for all images and other large page elements to finish loading. Unverse aims to minimise the amount of javascript needed to get stuff done, whilst trying to remove the hassle of getting your code to work with varying DOM implementations in different browsers. This is a common aim and there are a lot of ambitious and excellent libraries out there attempting the same sort thing. But, compared to Unverse, they are all enormous.