Awesome JavaScript obfuscation. The linked post shows a JavaScript code that pops up an alert.

($=[$=[]][(__=!$+$)[_=-~-~-~$]+({}+$)[_/_]+  
($$=($_=!''+$)[_/_]+$_[+$])])()[__[_/_]+__  
[_+~$]+$_[_]+$$(_/_)

This shows how difficult is to detect a client-side attack and also demonstrates why we must design our networks to detect malicious activity once the defenses fail.

The blog post talks about the following presentation in Blackhat DC 2011.