I haven't read this whole thread through, so I don't know if this has been mentioned or not. Several months ago, about the time The Dark Knight came out in theatres, a book came out called Becoming Batman. Essentially the author researched what it would take to become a Batman-style superhero and wrote a "How To" book on the subject. I haven't read the book, but I did listen to an interview with the author on the radio. This is the gist of what he writes in the book.
Physical Training: You would need to spend at least a decade in Asia training in one of the world's deadliest martial arts. Either in China at a Shoulin temple learning Kung-Fu, or in Japan studying Ninjitsu under the tutaledge of a Master Ninja.
Forensics Training: You would need to learn how to collect evidence without contaminating it, process it, and interpret the results. In other words, you'll have to become a trained CSI. And just like on the show, you'll need to be proficient and knowledgable in all aspects of crime scene investigation and not just your own little area of expertise (like it is in real life).
Psychology Training: You will also need to study Forensic Psychology, Criminology, and Sociology in order to become a proficient profiler. You'll need to know the difference between Modus Operendi and a criminal signature.
Costume: You'll need to make a costume to both hide your identity and strike fear into the hearts of the criminal element. While many people have made remarks of "spandex clad heroes", I would opt for kevlar. It's the same material flack jackets and bullet proof vests are made out of. It's very difficult to cut through, and can even stop certain callibre bullets (it'll hurt like hell, but it'll stop them). I'd also advise purchasing a bullet proof vest, something designed to be inconspicuous, to wear underneath. You should also choose a target to print on your chest to draw enemy fire away from your head and towards your body armour (Batman's bat, Punisher's skull, Spiderman's spider, etc). Of course you will need to wear a mask. This is to hide your true identity from the police as much as from the criminals you're going to be pissing off. Taking the law into your own hands and becoming a vigilante is as illegal as selling crack, running a brothel, or beating someone up and stealing their money. If the cops learn who you are, you'll be arrested and treated no differently than the criminals you're trying to rid the streets of. If the criminals learn who you are, they'll come after you, your friends, your family, whomever.
Equipment: If you're going to be a Batman-style superhero and just beat up the badguys and leave them for the cops with the evidence needed to convict them, then you'll be needing extendable batons, handcuffs, pepperspray, pepper guns, tasers, and maybe some rope. Most of these things can be purchased at any military surplus store. Some you'll need to order through the internet (depending on where you live, I live in Canada so tasers are illegal for civilians to carry here). If you can't find handcuffs at your local surplus store, try your local BD/SM Bondage Shop (buy the expensive ones, the cheap $10 ones have a safety catch allowing the person cuffed to just slip out of them). And of course any hardware store will have rope.
Of course if you're a Punisher-type hero and want to just blow the drug dealers and the pimps away, you'll need to buy plenty of guns and ammunition.
As for choosing a name, comic book heroes get their names all sorts of ways. Some choose their own names (Batman & Dare Devil for example). Some are named by the media or other sources (The Hulk comes to mind). Others just sort of happen (Spiderman was Peter Parker's ring name when he was working as a professional wrestler for some extra cash). On the daytime soap, Days Of Our Lives, there was a masked vigilante who called himself The Pacifier (because after videotaping criminals breaking the law, he would beat them up, tie them up for the police, then leave the video tape behind and a baby pacifier haanging around their necks).
