We do Enterprise web development for a major University and leverage Java as our core language. We use a combination of software including Java, Hibernate, and Stripes to manage student information for tens of thousands of students. We have found this to be an excellent combination.
Recently, I have been experimenting with upgrading our platform by using Groovy for unit testing and batch jobs. Groovy is basically dynamic Java. It is 99% compatible with Java so essentially you can drop in you Java code and it will run except on a few edge cases. This is because Groovy compiles down to the same bytecode that a similar Java class does. You can't tell the difference except the smile on your face as your coding is reduces by approximately a 6:1 ratio.
Groovy incorporates some of the cool features that other 'dynamic' languages such as Ruby and Python have been rubbing in us Java guys noses for quite awhile such as closures, operator overloading, and autoboxing. A good book on Groovy is by Scott Davis' called "Groovy Recipes" (ISBN 10 0-9787392-9-9). Groovy is the ticket to moving Java into the 21st century.
If you are feeling adventurous and are starting a project from scratch, I suggest another web framework called Grails. This convention based framework and development environment uses the Groovy language and leverages popular and solid frameworks available such as Hibernate and Spring. A good book on Grails is "Beginning Groovy and Grails: From Novice to Professional" (ISBN: 978-1-4302-1045-0).
Dynamic Java is here folks and it runs on the JVM which is where things seem to be heading (JRuby, Jython,..). Why use a language that must be transformed to use the JVM? Instead use a language that the JVM was designed for!
