Cypal Studio for GWT is a set of Eclipse plugins for making GWT development easier. It currently helps you in:

• Creating a module
• Creating a remote service
• Maintaining the Async file
• Runing your app in hosted mode
• Compiling your app to JavaScript
• Deploying to an external server
• Exporting as WAR operation

Look into the docs for more information or view this screencast for your first GWT app. If you want to contribute to the project, please read this.