Adding External Javascript to Magento’s Head
Magento’s head template (in 1.6.1 at least, but probably other versions as well), includes a call to $this->getChildHtml();. When called with no paramaters, this method renders all the child blocks of a template. That means you can add any child block to the head block, and have it rendered in the document <head>. Useful for using CDN Javascript, web fonts, etc.