If you are into great but simple applications, then excssive is one of the sites you might like. Why? Because is hosting a simple but yet very useful drag and drop CSS compressor. The idea of the site is to let you drag into it unlimited number of CSS files and its going to automatically compress them.
The web CSS compressor also merges all the files into a single one and you have an option to reorder the files again with drag and drop (the output of the compressed CSS will have the same order as you settled). So, if you don’t have an dynamically CSS compressor tool, bookmarking this site is a must!
Also, if you want to check the source code/modify it/etc you can do that on the application Git page.
Online and simple CSS compressor