Aaron T. Grogg

This plug-in takes the URL, chops it into pieces, and adds each “piece” as an additional 
class to the <code>body</code> tag.
Meaning, if your page’s URL is: 
http://www.example.com/2012/02/24/wordpress-plugin-add-url-slugs-as-body-classes/ 
Your page’s <code>body</code> tag would have at least these classes: 
 2012 02 24 wordpress-plugin-add-url-slugs-as-body-classess
It gets much stronger when you start thinking about Categories or nested Pages: 
 http://www.example.com/category/wordpress/ 
which would add: 
 category wordpress 
while: 
 http://www.example.com/movies/star-trek/wrath-of-khan/ 
would add: 
 movies star-trek wrath-of-khan
This allows you to very easily add custom CSS and/or JS to these pages based on these new CSS classes.
Please let me know if you have any questions/suggestions/thoughts, 
Atg 
http://aarontgrogg.com/ 
aarontgrogg@gmail.com

Add URL Slugs as Body Classes

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.

Add URL Slugs as Body Classes vs Add Custom Body Class