What is Google Analytics’ __utm.gif used for (You know that 1px × 1px gif image that loads on every page with Google Analytics)?
I see my screen resolution and other stuff in the URL. Is that how they send all the site’s data back to their servers? With a get request on an image? Cause that’s kinda uber clever!

it is a web beacon. Read this: https://en.wikipedia.org/wiki/Web_beacon