Sea.js
A Module Loader for the Web
Almond
A minimal AMD API implementation for use after optimized builds
Webpack
Packs CommonJs/AMD modules for the browser. Allows to split your codebase into multiple bundles, which can be loaded on demand. Support loaders to preprocess files, i.e. json, jade, coffee, css, less, ... and your custom stuff.
Nanobar
Very lightweight progress bars. No jQuery
Head js
The only script in your HEAD. Head JS loads JavaScript files in parallel like images without blocking the page. Your page will be faster. Even with a single combined file.
LABjs
Loading And Blocking JavaScript: On-demand parallel loader for JavaScript with execution order dependencies