Face on Mars
The apparent "Face on Mars" is a perfect example of one of EdSkeptics favourite things - pareidolia. The term is usually used to describe the apparent ability of humans to ascribe patterns to data or incoming stimuli without there actually being any. For our purposes we just use it as a way of sharing pictures of objects that look like funny faces.
The formation is in a region known as Cydonia and is seen as evidence of some kind of extra-terrestrial existence. Later images taken by more modern space imaging platforms have revealed the formation to be fairly standard in terms of other Martian features and that it's "facial" appearance seems to be entirely dependent on viewing and lighting angles.