JetBrains markets their IntelliJ IDEA as "the most intelligent Java IDE." Having used commercial and open source Java IDE's spanning from JBuilder to Eclipse, I must admit that IntelliJ is pretty special.
Everything one would expect from a modern-day IDE such as accelerator keys, code completion, efficient search, refactoring, and more comes naturally to the product. What raises the bar beyond its competitors is full Java EE 6 support, extensible framework support for such platforms as Android, Google App Engine and Google Web Toolkit, integrated UML tools, multiple language support (including Flex, Groovy, PHP, Python, Ruby, Scala, and many others), support for a number of VCS's including Git and Subversion, and deployment and debugging on an array of application servers ranging from open source Tomcat and JBoss to commercial Weblogic and WebSphere solutions.
Considering the broad range of features and the ease with which these capabilities are installed and accessed, IntelliJ is unquestionably one of the smartest choices a Java developer can make to be as productive and prepared for the broadest range of work as possible.