"Where does he get those wonderful toys?", Jack Nicholson asked rhetorically.
It's a valid question; the list of Batman accoutrements reads like a shopping list for the local Toys 'R' Us.
Batmobiles, bat-planes, bat-boats, bat-copters, bat-cycles, bat-whirlygigs, bat-skates, batarangs, bat-computers, bat-skies, bat-shark repellant, etc. - it just goes on and on. Bruce Wayne has to be a multi-millionaire just to pay for the whole thing. Consider, too, that all of this stuff is often destroyed or used up; I don't think Bats stops to recover each one of those little bat-shaped dart-things he throws at people.
Considering the dollar value of all this stuff, there must be some kind of Batman mini-industry at work in Gotham and elsewhere, where people and companies produce everything he consumes. You see where I'm going with this? Batman keeps people employed. His activities produce economic benefits for Gotham, in terms of trickle-down economics and consumer spending. Heck, if this were the real world, he could act like a professional NHL hockey team and use that clout to extort tax benefits and other hand-outs from the municipal and state governments.
One of the best known bat-gimmicks is the bat-signal, located on the roof of police headquarters in Gotham City. It's a big spotlight with a black bat painted on it, used by Police Commissioner Gordon to summon Batman when necessary.
Yes, I'm sure that encrypted cell phone conversions are more apropos today, but the bat-signal wins out on sheer dramatic impact. Mind you, it has never been made clear exactly what the signal is shining against. A blimp, perhaps? Or maybe Gotham just has a perpetual cloud cover. It's probably best not to ask questions like this.
Even with the signal, the Gotham City Police Department (GCPD) has always had an on-again, off-again relationship with Bats. For the most part, Gordon understands that Batman would be out there anyways, so he feels that it makes sense to utilize him. For those of us with some understanding of constitutional law, this reasoning is flawed. Batman regularly commits acts that the GCPD cannot do, under the limitations set out by the Constitution and relevant civil rights acts. By condoning Batman's actions publicly, Gordon can't distance himself and his department from those actions and any lawsuits or court dismissals that could result, since Batman could be perceived to be an agent of the police. A pragmatic police department would disavow any knowledge of Batman and his actions, giving themselves the plausible deniability they need to take advantage of them.
Whoops; my cynicism is showing again, isn't it?