Richard Venancio

This plugin used to get de sub menu refers the current item menu, and show this with a menu, for exemple a sub menu left.
Supose you have a big main menu, and this have a lot submenus, so, to show yours submenus in a side of your site, you create one new menu in wordpress for each submenu you have, and create codes to define which submenu you show, according the location in hierarchy’s menu you are.
This is very tiring and biggest, for just show the submenu, then this plugin do all things for you, but don’t create any menu, it just get the submenu according the main menu.

RVSubMenu

This plugin used to get de sub menu refers the current item menu, and show this with a menu, for exemple a sub menu left.

jcollings

JC Submenu plugin allows you to automatically populate your navigation menus with custom post_types, taxonomies, or child pages. An easy to use plugin created to be a lightweight menu extension.
Also output a selected section of your dynamic menu through our advanced submenu widget.

JC Submenu

JC Submenu plugin allows you to automatically populate your navigation menus with custom post_types, taxonomies, or child pages.

RVSubMenu vs JC Submenu