I've been designated by two such entities to represent people in Virginia who are members in case of serious legal problems. Those are the only ones I really know anything about and it's been a while since I read up on what they're doing. But the last time I checked, the Armed Citizen's Legal Defense Network is basically an educationally-oriented nonprofit which has a funded foundation that will pay immediately to your attorney if they think your case is legit. The amount they pay probably won't cover your total fees if you've actually fired a gun and hurt someone, but will be enough to get a lawyer cranked up and talking to you. The big bonus with them, as I see it, is the educational emphasis: they put out a bunch of DVD's and have an online web-forum for members and publish new information all the time. Although a lot of the defensive carry information you get from people other than myself will be sort of generic, and some of it won't apply in Virgina, theirs is generally good stuff. And they gave me a nifty hat for signing up as their attorney in Virginia. The other one is the United States Concealed Carry Association. Like their name says, they emphasize concealed carry, and don't directly fund legal defense. They have a contract with an insurer who will either pay for or provide legal services (through an independent attorney of their choice) in civil and criminal cases using different payout rules for each. In civil cases their first option will be to hire their own attorney (sort of like getting court-appointed counsel, in my estimation), but may, instead, pay for yours (probably at a negotiated reduced rate). In criminal cases you have to fund the litigation yourself and if the case ends other than with a conviction, then they'll reimburse you.
The big difference for someone who needs legal defense is that the former provides an immediate but limited payout and the latter provides reimbursement but potentially covering your legal expenses.
Of the two, I'd go with the Armed Citizen's Legal Defense Network. But both appear to be reputable. Membership cost for each is fairly cheap, I think, and there's no rule that says you can't do both. There are links to each on my website (scroll down to the banners).
I always tell people to put about six thousand in ready cash somewhere so you or someone you trust in an emergency can put their hands on it. That's a good thing, not just because of legal defense needs, but sudden medical costs, computer disasters, etc. My wife calls it a "rainy day fund". You ought to have one, even if it means putting just ten dollars away with every paycheck. But six thousand bucks will get you a good lawyer, at least initially, if you're sued or charged with a felony, and will more than cover the cost of most misdemeanor charges.
By the way, there is one entity that started out by blatantly copying me, my style, and my website and offering low-ball "retainers" to cover the risk of a need for legal services in defensive situations. They've gotten a lot better since that time about distinguishing themselves from me (I had to send them a "cease and desist" letter), but it is my opinion that what they're doing is illegal. First off, what they're really doing is an unregistered insurance program that does not appear to be funded by any underwriter, and secondly, what they're calling a "retainer" is really an insurance premium. A true retainer is an amount of money you pay merely to say that so-and-so is your attorney, paid and earned on a periodic basis; it is not a payment for services, nor does it get you legal services during that period. It is possible, I don't know for sure, that what they're doing is charging a true retainer and then telling people their case doesn't merit free legal services so they have to pay up anyway. But that's the only way what they're calling a "true retainer" could actually be a retainer.
Another thing to watch out for regarding legal services is people who advertise in phone books and on the internet, with two columns of various practice areas with about thirty items in each column. Someone who does wills and divorces, or even general criminal defense, generally does not understand personal defense law. These are people who specialize in WCITD, pronounced, "weck-it-tid", an acronym that means, "whatever comes in the door". The other group to watch out for are the "plea-bargain factories". They'll charge a fixed fee for criminal defense at a rate lower than what, for example, I would charge, because a lot of people are shopping for the lowest cost. But these guys routinely treat the client as guilty, never actually prepare for trial, never seriously consider what defenses the client may have, do not interview potential witnesses, and will come to court often meeting the client for the first time on the day of trial. They go to the prosecutor and see what "offer" the prosecutor will make, then go back and twist the client's arm telling the client why he has to take the deal or face a long jail term.
A good lawyer will always treat going to trial and trying to win as the first and best option. Plea bargains are for damage control only, where the client really is guilty of whatever the charge is, and just needs to have some certainty about keeping the punishment as bearable as possible. But doing a plea bargain is about two hours' work, so the plea bargain factories are making money hand-over-fist. Going to trial is expensive, because it's real work and takes time. But it's the only option if you don't want to be found guilty of a crime you didn't commit, want to preserve your right to an appeal, and on appeal (assuming the case started out in a non-jury district court) to preserve your right to a jury. Also, after you've pleaded guilty, you no longer have a right to refuse to answer questions - the Fifth Amendment right doesn't apply when you've waived it by pleading guilty.
One way to find a good lawyer is to talk to people who work for the Sheriff's Office as courtroom bailiffs. They see it all and hear it all, and after a while, they get so they know who's good and who isn't. And keep in mind that lawyers, like humans, generally, fall into three groups: some are really good, some are really bad, and most are average. If you were involved in a car accident at two a.m., would you want an "average" surgeon working on you? The time to prepare and find a good lawyer is now. How you pay for it will be another thing all together. Sign up for those programs if you like, and figure out which friends and relatives will come to the plate for you when you're in trouble. But do it now.