Web Utility Package

Http Proxy Servlet
Both Flex and AJAX have Browser security restriction that can only allow them to access the web server where they originally come from. In order for your Flex and AJAX app to access the web service on the Net, you need to deploy a proxy onto the web server they can access. In PHP, you can use this php proxy (code). In Java, you can use this proxy servlet (code).

Shell Servlet
If you want to issue commands to the web server and tell it to run this command. You can do that with Shell Servlet. With this, you can do Web Administration online, even through WAP phone. 

Reference:

http://www.servletsuite.com/servlets.htm