How can I port a legacy Java/J2EE website to a modern scripting language (PHP,Python/Django, etc)?
A lot of the recommendations being given here are assuming you -- and just you -- are doing a full rewrite of the application.  This is probably not the case, and it changes the answer quite a bit
If you've already got J2EE kicking around, the correct answer is Grails.  It simply is: you probably already have Hibernate and Spring kicking around, and you're going to want the ability to flip back and forth between your old code and your new with a minimum amount of pain.  That's exactly Groovy's forte, and it is even smoother than JRuby in this regards.
Also, if you've already got a J2EE app kicking around, you've already got Java developers kicking around.  In that case, learning Groovy is like falling off a ladder -- literally.  With the exception of anonymous inner classes, Groovy is a pure superset of Java, which means that you can write Java code, call it Groovy, and be done with it.  As you become increasingly comfortable with the nicities of Groovy, you can integrate them into your Java-ish Groovy code.  Before too long, you'll be writing very Groovy code, and not even really have realized the transition.
I want to move a legacy Java web application (J2EE) to a scripting language - any scripting language - in order to improve programming efficiency.
What is the easiest way to do this? Are there any automated tools that can convert the bulk of the business logic?