NetTool is a developer tool for monitoring and manipulating application-level network messages, particularly useful for debugging webapplications and web services. There are two components to NetTool: the HTTP Client, and the TCP Tunnel.
Bugkilla is a set of java tools for the functional test of J2EE WebApplications.
Specification and execution of tests will be automated for web front end and business logic layer.
One goal is to integrate with existing frameworks and tools.
araSpect is a server side object inspector for webapplications. Through a web interface you can drill down in your server side java beans. It is very easy to install and can be added to a deployed application. There is special support for Struts.