The play framework
http://www.playframework.org/ is similar in concept to develop in Django or Rails. That is, no compile-package-deploy. Change the code and refresh the browser, see source code for errors etc.
Go to the site to see the video.
from the site:
Fix the bug and hit reload! Edit your Java files, save, refresh your browser and see the results immediately! No need to compile, deploy or restart the server.
Stateless model Play is a real "Share nothing" system. Ready for REST, it is easily scaled by running multiple instances of the same application on several servers.
Efficient template system A clean template system based on Groovy as an expression language. It provides template inheritence, includes and tags.
Resolve errors quickly When an error occurs, play shows you the source code and the exact line containing the problem. Even in templates.
All you need to create a cool web application Provides integration with Hibernate, OpenID, Memcached... And a plugin system.
Pure Java Code with Java, use any Java library and develop with your preferred IDE. Integrates nicely with eclipse or netbeans.
Really fast Starts fast and runs fast!
P.s. version 1.1 will have support for Scala