controljs

http://code.google.com/p/controljs/   

http://stevesouders.com/controljs/

A JavaScript module for making scripts load faster.

 

Features:

• downloads scripts asynchronously
• handles both inline scripts and external scripts
• delays script execution until after the page has rendered
• allows for scripts to be downloaded and not executed
• integrates with simple changes to HTML . no code changes
• solves some document.write async use cases
• control.js itself is loaded asynchronously