So I’ve packages up one of my libraries and gave it a nice interface in WordPress so others can use and enjoy it. This plugin gives you much greater control than WP Super Cache (which works well in tandem with this plugin) or wp minify does by allowing you to decide which assets to combine and optionally compress. You can try it out by searching mncombine in your admin plugins > add new screen or downloading it directly.
What is does
There are two modes, development and production, the ability to force the files to print in the header or footer*, the use of Google Closure as a JS compiler, and finally the ability to pick and choose which files, including dependencies, should be combined.
*forcing head compiles can fail on JS files queued after the call to wp_head(). The plugin will, in this case, render the late queued files in the footer as originally intended.