Say what you will about self expression, but graffiti and street art are two different things in my book (check out this Huff Po article for more on the topic). Some street art aims to make a political/societal/historical statement (ala Banksy), and some of it is meant for pure pleasure. Take the work of Roadsworth, for instance, who started making waves in his hometown of Montreal in 2001. "At first glance, a pedestrian may not even notice that there’s anything amiss, and I’ve always liked the subliminal aspect of this kind of street art," he says in this article. I, for one, know it's natural to keep to yourself when you're shuffling from place to place in a big city. But on your next commute, try opening your eyes and observing the people, places, and walls around you. If you're lucky, you'll spot a few hidden gems.