Google Web Toolkit showcase: TeamPostgreSQL
teampostgresql.com
The application uses a sophisticated AJAX web client and as such is a good showcase for what can be done with GWT in that arena. The interface is complex yet dynamic and customizable and service invocations are fast and immediately reflected on the client.
The server is realized by a slightly modified Apache Tomcat, supporting the well-known JEE features with regards to security, deployment, dynamic configuration etc.
If you'd like to check it out, the download is available at: http://www.teampostgresql.com