Anil Ankola

This is a really simple way to add body class and is especially useful if you are creating a theme or website.

Add Custom Body Class

Use this plugin to add a custom class in the HTML body tag.

Mikkel Rommelhoff

An add-on for <a href="http://www.gravityforms.com" rel="nofollow ugc">Gravity Forms</a> which allows you to wrap form items in a div with a custom class for styling purposes. Supports conditional statements.
Features of this plugin:
<ul>
<li>Add a wrapper (div) for the form items.</li>
<li>Includes option to add a custom class for styling.</li>
<li>Supports conditional statements.</li>
<li>Autocomplete of wrapper to properly close all HTML tags.</li>
<li>Auto-delete of wrapper to properly close all HTML tags.</li>
</ul>
Available Languages:
<ul>
<li>English</li>
<li>Danish</li>
</ul>

Wrap form fields in Gravity Forms

Nice plugin, too bad its stolen from another plugin.

nicely stolen

Extends the Gravity Forms plugin - Adding a new field type to wrap field items in a div with custom classes.

Add Custom Body Class vs Wrap form fields in Gravity Forms