Gotta have time to waste.
At one point, in the early days of this forum, I saw someone accidentally type in a smiley that wasn't initially in our list. I was so intrigued that I Googled stuff like "SMF hidden smileys" before eventually finding a list of all the smileys, as well as how to type them in. Which led to me making a mega list in Non Sequitur. It's been linked in my signature ever since.
In case you're new and are wondering why this one guy has "Smileys, 'nuff said" for a signature, there ya go.