neoslab

Powered Minifier allow you to reduce your page load and increase your performance by minifying your HTML source along with all the CSS and JS code present in your markup.
<h3>License</h3>
Good news, this plugin is free for everyone! Since it’s released under the GPL, you can use it free of charge on your personal or commercial site.

Powered Minifier

Honestly it's the best minifier plugin for Wordpress 

Simply Excellent

Reduce your page load by minifying your HTML source along with all the CSS and JS code present in your markup.

Scott Taylor

Similar to what we use on eMusic – this software is still experimental, but take a look!
Automagically concatenates JS and CSS files that are output in wp_head() and wp_footer() – stores / serves them from Memcached (if installed) or Database. In a load-balanced environment, the generation of flat files can be expensive and hard to distribute. Minify takes advantage of Memcached and Site Options / Transients to do the work once and share it among all servers in your cluster. File names are dynamically-generated to allow cache-busting of a CDN like Akamai that doesn’t always cache-bust by query string.
New .htaccess rule! 
 RewriteRule ^([_0-9a-zA-Z-]+)?/?wp-content/cache/minify-(.+)-(.*).(css|js)$ /wp-content/plugins/minify/make.php?hash=$2&type=$4&incr=$3&site=$1 [L]

Minify

Automagically concatenates JS and CSS files that are output in wp_head() and wp_footer()

Powered Minifier vs Minify