Under fluorescent lights and through a microphone that kept shorting out, Joe Fontana cleared his throat and addressed his small audience. ''The insurance companies are going berserk,'' he said. ``There's no limit to what they will charge homeowners. We have to find a way to counteract this or the people in this city are going to be killed.'' Then Fontana led the 38-building-strong Miami Beach Condominium and Homeowners Alliance in devising a plan to try to stop the runaway cost of windstorm insurance. Consumers like Fontana, fed up with double- and triple-digit insurance rate increases, are beginning to band together. Decades-old home and condo associations, newly formed grass-roots organizations and accidental neighborhood juntas are cropping up around the state to press for solutions to Florida's escalating insurance crisis.