LimeJS is a HTML5 game framework for building fast, native-experience games for all modern touchscreens and desktop browsers. Its goal, according to the creators, is quite clear and simple: to provide an easy way to build good game experience without thinking about inner workings.
Check LimeJS‘s official site or its GitHub repository.
Baseline is a CSS framework that aims to be a basic typographic layout and build a simple grid system, including style for HTML forms and new HTML 5 elements.
This framework uses the font metrics to line up headlines, paragraphs, form labels and other elements on the page baseline, tending to create a nice fixed layout.
Download the zip to test the framework and see some examples.
Cartgen is a vector-based, client-side framework that renders maps in HTML 5 combining the canvas element and javascript. Maps are styled with GSS, an accessible specification based in CSS and JSON. You can read more about Cartagen in their Wiki.