IntelliJ IDEA is an advanced IDE developed by JetBrains and focused on
developer productivity.  The community edition features:
* An intelligent code editor that understands Java code; provides
  refactorings, code inspections and intentions, and allows for
  fast code navigation.
* Integration with such tools as JUnit and TestNG, Ant and Maven,
  and popular version control systems including: CVS, Subversion
  and git.
* XML-Java interoperability and comprehensive Groovy programming
  language support.
* The Swing UI designer complements the suite of tools for
  developing Java desktop applications.

The difference between intellij and intellij-ultimate can be found at

http://www.jetbrains.com/idea/features/editions_comparison_matrix.html

WWW: http://www.jetbrains.com/idea/