Which snake species is the longest?

Giant snakes are one of the few things that make even Indiana Jones sweat, and there's a whole world of slithering serpents vying for the title of nature's ultimate measuring tape with fangs. From ancient fossils that make today's giants look like garden hoses to living legends that can literally swallow a deer whole, the snake kingdom has produced some serious contenders. Which snake species currently holds the crown as the longest?