I was thinking on influence of earth/modern culture in the planes within the urban planescape and suddenly super heroes came to mind, do you think some modern humans would be influenced to take on masked persona and attempt to fight off evil in Sigil or similar places in a horrible Cliché fashion? I can just imagine an "O-Man" running around Sigil with a cape in tow, to appear before evil do-ers as a bad Omen for business.
Now some might think that adventurer's have been doing this kind of thing for ages. However, I imagine with the increased in population and with modern culture, Fame is far more of a curse that it would be in a traditional game. Of course apathy has always been a part of my sigil and I don't think that will change (people still don't care what dragon you slew) but with Boy bands and such other unfathomable horrors introduced into planar culture, I imagine the masses whipped into frenzy easier under certain circumstances. Such as in the presence of a famous Rock star ("I have a piece of his hair!!!" "I got some of the skin from his back!!") Or other such celebrities. The point, fame may be less than desirable and adventurers may want to keep a lower profile in some cases and perhaps even adapt an alternate identity! Such as O-Man!
where do think captain autism came from he is the avatar of stupidity and in Mps he could just be some guy that flys around