Grails is a framework to quickly build web applications. It's based on Groovy. You define the model, run two commands from the command line and you're set with a simple CRUD UI where you can edit your model in a web browser.
Web only, a lot of nice ideas but you can't have parent/child relations because of this bug which will hopefully be fixed in 1.0.5 release. For serious development, you will need one of the AJAX/Rich Client plugins because Grails doesn't come with very powerful widgets.
