philipwalton

WARNING: This plugin is no longer being supported by its developer and may not work with future versions of WordPress. A replacement by the same developer is available called <a href="https://wordpress.org/extend/plugins/pw-archives/" rel="ugc">PW_Archives</a>. It’s faster, more efficient, and implements the latest WordPress security features.
This plugin makes the posts in your nav easily-groupable by month and year. It gives you 
quite a few easy-to-implement options that allow you to customize both which date groups are 
listed as well as how the markup is structured.
Perhaps the primary benefit of this particular plugin over other plugins that do similar 
things is its ability to enclose the post count within the anchor tag. This solves countless 
problems for anyone using the CSS style display: block on anchor tags, which produces the 
undesirable result of forcing the post count down to the next line.

Simple Nav Archives

Allows you to group your archives by month and years with several customization options.

joe_bopper

Adds search box as a choice of item in navigation menus admin area.
Features include:
<ul>
<li>now compatible with the WordPress appearance customizer,</li>
<li>search box available as a choice in the admin area for navigation menus,</li>
<li>as many boxes can be added to a nav menu as one likes,</li>
<li>search boxes can be added as children of other menu items (useful for, e.g., mega-menus),</li>
<li>capacity to change button text, placeholder and css classes from the admin area to each search box,</li>
<li>hooks to modify output (see FAQ and/or code comments),</li>
<li>very lightweight,</li>
<li>in keeping styles, html, behaviour, etc., with wordpress defaults,</li>
<li>works straight out of the box, no configuration needed.</li>
</ul>
<h4>Those wanting to translate this plugin, please do.</h4>
I believe the plugin is in a translatable state and I’ll do everything I can to help in translation. It should be relatively quick as there isn’t much text to the plugin.

Bop Search Box Item Type For Nav Menus

I like the way it behaves like any menu item so you can position and decorate it how you want. Thanks to Joe for putting me right on how to get at the placeholder text.

Nice Plugin

Adds search box as a choice of item in navigation menus admin area.

Simple Nav Archives vs Bop Search Box Item Type For Nav Menus