Miele - www.miele.co.uk
Miele produce high quality white goods. They have a set of over 70 engineers who travel around the country fixing applicances and the system I worked on is the communication between the head office and the engineers on site. It gives them a set of calls for the day, and uploads information about whether the job has been finished and what the cost should be.
When I arrived the system was already in place and they needed some maintenance doing (most importantly they couldn't increase the prices), and the programmer who had written the system had left. All they had was a folder with the source code, and in one day on site I compiled all the source code up using eclipse, put it in place and got the test system working. Since then I have done lots of maintenance on the system including adding extra screens, making the back end more efficient, making the prices easy to change, and many others.
I think the programmer who wrote this system was learning java because he used every api available. The front end screens are written in Swing, the backend is container managed entity beans, in between he used SOAP, XML, Ajax tag libraries, Jboss, Tomcat, Jsp's and Servlets.