There's apparently even a documentary about one real-life Justice League - they call themselves Superheroes Anonymous. Okay, it's actually an annual conference for real life superheroes, not a team.
What's fascinating is finding out about how these Reals act and what ostensibly motivates them, and also reading between the lines and speculating about them. This is not Watchmen, Nite Owl never had a poster of Captain America in his living room. I think this is the biggest difference between our world and any comic book universe, since none of them have 80 years' worth of superhero comics establishing what superheroes are before anyone ever tried putting on costumes and fighting crime.
Legally speaking, Real-Life Superheroes are merely vigilantes, but I think it's useful to distinguish them from other vigilantes. Regular vigilantes, masked or not, tend to harass and kill minorities and other groups not part of "proper" society - I recall the white New Yorker and mugging victim who shot two guys for the crimes of being black and in the same subway car as him, while there are South African vigilantes who harass Namibian immigrants when they're not executing drug dealers and burning witches. Being a vigilante means abandoning the law, after all, and to me it always seemed hypocritical of Spider-Man to break the law by attacking criminals while afterwards expecting the law to serve his purposes by depositing said criminals to the police all webbed up (and let's not even get into the legal issues - what, police are supposed to arrest someone who was obviously beaten into unconsciousness because a note pinned to his chest says he's a mugger?). The closest Real-Life Superhero to this ethos would have to be Angle Grinder Man, who removes parking boots from cars as part of his struggle against "the repressive shackles of a corrupt government".
No, what distinguishes the Reals from the regular vigilantes is that there's an element of play, of performance, in their actions. If they only wanted to hide their identities, they could just wear ski masks, but they go whole hog and make up costumes and bombastic names for themselves. They consciously emulate their fictional role models, as is obvious from reading the membership criteria of the World Superhero Registry: members must have a costume, must perform Heroic Deeds, and cannot be a paid representative of any organization. And witness the name of Superheroes Anonymous - obviously a play on Alcoholics Anonymous, and a self-conscious recognition of the fannish obsession and the possibility for ridicule bound up in being a Real-Life Superhero.
So what we have are a few hundred people, mostly Americans, who are essentially playing dressup and who only occassionally help out the odd person here or there (in fact, it seems to be a common complaint of Reals that most of the time, they drive around all night without spotting any crime). Skimming the World Superhero Registry, it appears that a lot of their activities involve things like helping stranded motorists, shoveling the sidewalks of seniors, looking out for the homeless, and other mundane, non-violent stuff. The most realistic comic book portrayal of this lifestyle would have to be Twilight Guardian, who only patrols a few blocks in her suburban neighbourhood and who spends her time feeding deer jerky to cats and wondering about the lives of the people she glimpses (and whatever happened to that comic, anyway?). Any realistic portrayal of superheroics would have to include the realization that the police, with their greater resources, are actually much better at stopping crime.*
Still, while Reals are not rich, it's also obvious that they're not poor. Some of them buy special equipment, and just getting the material for a costume would cost money that someone living in a ghetto probably couldn't afford. Here we come up against another barrier that prevents a Real from being an effective crimefighter - ignorance. Theoretically, with the right contacts and information an ordinary person could fight criminals effectively when not encumbered by due process, but how many middle class jerks know which bars the underclass frequent? How many junkies and hookers would roll over on the (usually gun-wielding) drug dealers in their neighbourhood a la Punisher and Batman for the sake of some middle class do-gooder, costumed or not? How many Reals can even talk in a way that wouldn't get them beaten up? Remember the scene in Training Day when the rookie undercover cop asked a dealer for "crack"? Remember how the dealer immediately knew he was a cop because he didn't use the proper street name for crack? That's what would probably happen if any Real tried to do the undercover thing.**
Perusing the stories about Real-Life Superheroes, there seems to be an element of pathos that runs through them, and unkind observers might say that it descends from pathos into bathos; that is, while Reals might have motivations that, while often pathetic, still evoke sympathy, the way that they act out their desires plunges the whole thing into the realm of the ridiculous. One might chart the Reals as being on one end of a comic book fan continuum, starting from the guy who watches superhero movies and ending with the guy who tries to be one. Remember the two out of shape pasty white guys posing in front of the Captain America poster?
I think it's instructive, though, to look at a Real-Life Superhero who most closely realizes the ideal type, the eidos, of the superheroic: Terrifica (1, 2), who is also my favourite Real. Terrifica patrols the bars of New York and tries to protect other women from the legions of sleazy guys who prey upon them. She has the Secret Identity: by day she works for a computer consulting company among unsuspecting coworkers, by night she rights wrongs in a gaudy costume among drunken bar-goers. She has the Origin Story: after getting dumped by her boyfriend when she moved to New York, mild-mannered Sarah created Terrifica to deal with her feelings of heartbreak and vulnerability. She has the Mission: to prevent women in bars from being taken advantage of by the pickup artists. She has the Special Vehicle, the Carrific, which I think is just the regular car she uses. She has the Superhero Gadgets, in this case the utility belt (aka fanny pack) where she stores her cellphone, lipstick, pepper spray, and other items necessary to doing good. She even has the Arch-Nemesis: Fantastico, the unapologetic philanderer who once seduced Sarah and whose bar room seductions she frequently breaks up.
She's definitely got the Superhero Drama. There's the Batman thing with trying to rescue her younger self every time she goes out in costume, especially the almost multiple personality thing where she refers to her civilian identity as being another person. But she's also got the Spider-Man thing of suddenly becoming outgoing and confident when she dons her mask. Just like Spider-Man, she's got her supporters and her detractors, and she even quit for a while, apparently because her coworkers were close to unmasking her. She must have had several moments of stomach-churning dread and anxiety at the prospect of discovery. And reading between the lines, it seems she's also almost as lonely as Bruce Wayne, since a lot of her nights are taken up by being Terrifica. Is she lonely because she's Terrifica, or did she become Terrifica because she's lonely?
The World Superhero Registry lists her as being retired, but even if she is, if you read the comments from her fans it's obvious she inspired quite a few people in her career. Yes, it's ridiculous to dress up in a costume and right wrongs as a way of dealing with your psychological issues. But it's also undeniable that she helped people along the way, even if it was just by being an example. She probably accomplished more for her mission than any of the costumed guys cruising around in their cars ever did for theirs. As a woman and as someone whose raison d'etre doesn't even involve violence, Terrifica is not the image of the comic book hero. However, her experiences certainly encapsulate that of the comic book hero: alter egos, temporary retirements, romantic entanglements and so on. How many of her male counterparts chomping at the bit for some costumed smackdown could claim a career as eventful as hers?
Here, then, is what it is to be a superhero in real life: the best Real-Life Superhero is the one who is the least like a comic book hero.
*One of the reasons I found the comic Kick-Ass stupid was because at one point the protagonist wondered why no one else had ever tried to fight crime in a costume, when these Reals had already existed for years. Of course, another reason is that Kick-Ass is actually effective, which only works in a fantasy.
**The biggest exception to this middle class uniformity would have to be Superbarrio, a Mexican street vendor who protects low-income neighbourhoods by organizing labour protests and files petitions, and who apparently doesn't ever try to use his fists to achieve his goals. However, it's clear that his model isn't the comic book superhero, but the Mexican luchadores, who do this kind of masked community activism all the time.