Ask HN: CSS and JS minification tool

I am looking for a simple script that would minify the CSS or JS file given as a parameter, in an efficient way.

I know about Yahoo's Java tool but it's overkill since I don't use Java AT ALL in my projects and would like to avoir having to install a JVM just for this.

The main technology I use is PHP but Bash or Python or Perl could be ok. This script would be integrated in our deployment mecanism, which is written in PHP.

Do you know any tool that could help me minify my files ? Or a lib that could be integrated into our deployment process ?

Thanks in advance.