I've been a professional Java developers for about five years. A big programming interest of mine is rule engines. I've worked quite a bit with both JBoss Drools and Sandia National Labs' Jess. Drools is my favorite by far.
In my spare time, I've been working on a side-project using Apache Wicket (my favorite for web development), Spring, Hibernate, JMS/ActiveMQ, Joda Time, SASS (Syntactically Awesome Stylesheets) and so on... basically, all of the cool, popular stuff.