[xentronium]

<shameless plug>

If you like that idea, you might want to take a look at library I am developing in my free time.

The idea is that you specify things you need (for example Mootools:Core and Mootools:More:FormValidation) and dependency manager pulls the required code with dependencies in correct order. It is in ruby, though (rack middleware + standalone packager).

http://xentronium.me/jsus/demo/

http://xentronium.me/posts/jsus-demo-packager -- some explanation

</shameless plug>