I am working on a web site that will help students practice their Scala programming skills. As I labored along, writing my JSF app code, I thought “this is silly—why not practice Scala at the same time?” But I like JSF and wasn't ready to jump to Lift or Vaadin.
With Eclipse, this isn't all that hard. Install the Java plugin. Make a dynamic web project in the usual way, using the Java EE perspective. Then, switch to the Scala perspective, right-click on the project, and, if all planets are aligned correctly, you will get a menu item “Add Scala nature”. (If they are not, see here for a manual approach.) Add your managed beans as Scala classes. Finally, switch back to the Java EE perspective, select the project properties, and add the Scala library JAR as a Java EE module dependency.