Below is the list of noteworthy public third-party plugins for the decompiler.
HexRaysCodeXplorer by Aleksandr Matrosov and Eugene Rodionov
Hex-Rays Decompiler plugin for better code navigation Here is the features list for first release:
navigation through virtual function calls in Hex-Rays Decompiler window;
automatic type reconstruction for C++ constructor object;
useful interface for working with objects & classes;
A simple list of various IDA and Decompiler plugins
More to come...
Happy analysis!