T Campbell wrote up the history of the emoticon for the first issue of ComixTalk back in February 2003. It’s an interesting article tracing the origins of those little sideways faces (plus it has some wonderful illustrations by Bill Duncan):
They look freakish. The noses are askew, the nostrils invisible. The eyes are beady little pinpricks, and the mouths have no lips, just parabolic cracks. They exist independent of anything else; they’re just a few bits of black on endless white space. Yet without the “emoticons,” the webcomics of today would be slower to recognize a fundamental human truth. We all recognize them – they look like typographic versions of the first faces any of us ever drew. And to understand their use, we have to go back in time to discover their prototype: the smiley-face.