I like the octocat because it's an interesting creation - it's my first time really seeing an octocat! Who knew they existed. The octocat's whisker's also come very close to the text on the right and go past the container. It has a left float and more than one negative margin.
I like the menu buttons a lot because when you hover over them they change. The text color changes from yellow to orange just by hovering the mouse over them and the area directly around the button you hover on also becomes darker and actually looks like a button is being pressed in. This effect is created by using a:hover with the webkit box shadow, box-shadow, and text-shadow properties.
This banner is very interesting because of the way it appears to pop out from the page. The color is a linear gradient using shades of red, has a negative left margin, and has an absolute position in the .note:before section of the CSS file.
This arrow is cool because of the way it gets so close to the text and goes outside of the text container. The arrow has an absolute position along with custom sizing and a right float.