How do the rest of you unfreeze water lines?

Turn on the tap the frozen line feeds first, so there's somewhere for the water and steam to go as it thaws. Then work from the tap end back towards the frozen section with a hairdryer, a heat lamp or towels soaked in hot water. No open flame, ever. A blowtorch on a pipe in a wall cavity is how houses catch fire. And once it's flowing, look for a split. Pipes often burst while frozen and only start leaking when they thaw.