Ramoonus

This plugin adds the Modernizr to your WordPress installation. 
Modernizr is a small JavaScript library that detects the availability of native implementations for next-generation web technologies, i.e. features that stem from the HTML5 and CSS3 specifications. Many of these features are already implemented in at least one major browser (most of them in two or more), and what Modernizr does is, very simply, tell you whether the current browser has this feature natively implemented or not.
For documentation visit http://www.modernizr.com/docs/

Modernizr for WordPress

The 2.8.4 version inserts broken javascript link. I posted a message about this in the support section for the plugin and the author has not responded or fixed the problem. Now, any site that I've added this plugin to can be broken if the user runs an update. 

Instead, if you need Modernizr, insert the following into your header.php file just after <?php wp_head(); ?>:

<script type="text/javascript" src="https://cdnjs.cloudflare.com/ajax/libs/modernizr/2.8.3/modernizr.min.js"></script>

Doesn't work - Plugin Defunct

This plugin adds the Modernizr to your WordPress installation.

canis1980

This plugin will send HTTP-headers to the client to ensure that Internet Explorer does not try to display the site in compatibility mode, 
which tends to break a lot of themes. This is the default behaviour for a lot of older Internet Explorer versions, when the site is identified 
as an intranet site. Some clients may also have the setting activated by other means.
This plugin will also tell Internet Explorer to start Chrome Frame, if that is present, as this will also enable the sites to display in a 
proper way.

Compatibility Mode Disabler

Disable Compatibility Mode in Internet Explorer for intranet sites. Also starts Chrome Frame if present.

Modernizr for WordPress vs Compatibility Mode Disabler