Squaretest - The Squaretest plugin for IntelliJ IDEA allows you to automatically generate the boilerplate code required for your Java unit tests.
codebunk - Realtime Collaborative Editor with Code Execution, REPLs and Chat
FindBugs for IntelliJ IDEA - FindBugs for IntelliJ IDEA provides static byte code analysis to look for bugs in Java code from within IntelliJ IDEA.
Floobits - Floobits brings real-time collaborative editing to text editors, IDEs, and now Atom.
IdeaVim - IdeaVim is a Vim emulation plugin for IDEs based on the IntelliJ platform.
coderpad - Collaborative code editor with in-browser, real-time execution. Conduct programming phone screens like a boss.