Douglas Crockford's JSMin ported to PHP. Open source and requires PHP5. Its a JavaScript minifier that trims out unnecessary whitespace, which chops down JavaScript files significantly.
A port of Douglas Crockford's command line JSMin in Perl. It removes extraneous whitespace and comments, but does not obfuscate the code.
Douglas Crockford's presentation on Advanced JavaScript. He covers topics such as inheritance, modules, debugging, efficiency and JSON.
Douglas Crockford examines the need for minimising the size of JavaScript code and compares minification and obfuscation. Obfuscation has the side-effect of introducing bugs because it changes variable names. The recommended approach is minification along with GZip compression. Since JavaScript is sent along in source form, it is impossible to hide that from a determined hacker