Sandy McFadden

This is a very simple plugin which requires almost no configuration.
All you need to do is go to the Appearence then Widgets area in the Admin Dashboard. 
Once you are there drag the BMI Calculator widget onto the widget area you would like it added to.
The only two settings are the title and the color. The color is the hex color you would like the results background to be.
A lot of the code was adapted from 
<a href="http://codereview.stackexchange.com/questions/21581/calculating-body-mass-index-bmi" title="Inspiration Code" rel="nofollow ugc">Stack Exchange Thread</a>

Healthy BMI Calculator

Adds a shortcode and widget that will display a simple BMI Calculator on your site. Works with both metric and US style measurements.

brijeshk89

WP Health Check scans your WordPress installation and reports any security issues with your site. It will also recommend you the solution to ovecome the issues. The purpose of this plugin is to keep your WordPress installation Safe and Secure from hackers.
Features in WP Health Check 1.1 include:
<ul>
<li>Checks if you are using the latest version of WordPress</li>
<li>Checks if you are using the latest version of WordPress Plugins</li>
<li>Checks if you are using the latest version of WordPress Themes</li>
<li>Checks if it is possible to list the contents of the Uploads, Plugins or Themes directory</li>
<li>Checks if you have any inactive plugins which needs to be deleted</li>
<li>Checks if there is any user with the username “admin”</li>
<li>Checks if you are using the database prefix as “wp_”</li>
<li>Completely FREE</li>
<li>Licensed under GNU GPL version 3</li>
<li>Safe & Secure</li>
</ul>

WP Health Check

WP Health Check scans your WordPress installation and reports any security issues with your site.

Healthy BMI Calculator vs WP Health Check