I don't remember the site, but there was a company that used console.log() messages to hire engineers. There was essentially a request for developers who knew how to bring up the developer tools saying something to the effect of "You've found this so you must be an engineer, apply for a job at xyz@abc.com"

Even nerdier: I remember seeing a company that set a custom header on their server responses, like X-application-email: work@xyz.com.

Even though they aren't working together anymore, Girlfriend had an incredible one.

http://www.girlfriendnyc.com/

NSFW, so you'll have to inspect the source yourself.

Love these hahaha <3

anyone know other good ones?

Vox's is cool too. (go to page source)