Be sure you join this website. It certainly isn't a phishing thingy.

Actually, it is a phishing thingy.

This is what is known as a "browser in the browser" attack. It's pretty much created in HTML and some JavaScript and is meant to look like a Single Sign-On window. You can read about it on mr.d0x's website.

In addition to acting as a phishing example, this site is also a humble tribute to Homestar Runner!