I will concede that pictures help convey mood, alert readers to the topic quickly, and otherwise draw folks in. In learning how to use LiveJournal, I went looking for "user pics" to add to my posts. The LJ tool for creating them is really pretty easy to use so long as you have a digital image. And Google makes it easy to find images already in a digital format. Today's user pic is one of my favorites. I got it and several others from a site called Burning Well that contains lots of public domain images, nicely arranged in categories.
So, what do you think the user pic is? I love the glowing green light, but I'm not sure what it's from. The image was listed on the Burning Well site under the category "Textures." I think it has a science fiction feel, even though it's probably just a neon sign photographed with fuzzy focus. Context is everything, even for pictures.