I were wondering wich tool is the required, to minify and pack a .js file like the jquery.min.js is ??

Since I have quite a lot Javascript in my RIA, I'm feeling like minifying and GZipping it xD

I know there's a lot of tools on the web, but they don't do it like in the jQuery file ... 

So it's accesible that kind of tool ?? Where ??

Thanks in advance