Top Rated for IntelliJ IDEA Community

ToolWindow Manager

Allows availability of IDEA ToolWindow buttons to be controlled on a per-project basis.

RestfulToolkit

A toolkit for RESTful services development. 1.ONE STEP to navigate to service declaration.

Frame Switcher

Plugin for more convenient switching between projects/frames/windows than is alt-tab or Window menu.

SequenceDiagram

By vanco
SequenceDiagram for IntelliJ IDEA http://vanco.github.io/SequencePlugin. with this plugin, you can + generate Simple Sequence Diagram.

XPathView + XSLT-Support

The XPath part of the plugin provides a possibility to evaluate XPath expressions against any XML document opened in IDEA.

jsDelivr package search

Simple search and insertion of packages from https://www.jsdelivr.com.

Tab Shifter

This is a plugin with a bunch of actions to move tabs between editor splits and resize splits. Actions are added to "Main Menu -> Window -> Tab Shifter".

Embedded Linux JVM Debugger (Raspberry Pi, BeagleBone Black, Intel Galileo II, and several other IoT Devices)

Java Runner/Debugger for Embedded Systems/IoT Devices that run on any variant of the Embedded Linux Kernel.

WicketForge

WicketForge assists developers creating Wicket applications.