I've seen a few other people who do that, but it's a nifty idea. 3nodding Personally I like the emoticons we have, and while it might be fine to locate a few I could use regularly, trying to find thumbnails for every occasion would get tiring. If someone is that dedicated to doing it all the power to them!
Every time I have a "genius" idea I either forget it immediately or start writing out a topic and then realize that it wouldn't work or would be hard to implement.
That's a cool idea, though. I wouldn't have the patience for keeping stock of all the faces I would use, especially since we have pretty good emotes already, but I wouldn't mind seeing more people do this.