Awww..Isn't he cute?

[Fleetwood271]

So, what exactly is that under his two largest eyes, that looks like a mouth (like he's frowning)?

 

[Overread]

Jumping spiders are always cute! Though I've heard of many a tale of them jumping right at the camera+photographer and are often thought to react directly to their own reflection in the lens.

As for anatomy : The Earthlife Web - Spider Anatomy

have a look bit down on the Digestive Tract diagram for an idea of where the mouth is