For several years, my neighborhood was in the middle of a cellular black hole. In fact, up until a few short months ago, most cell services failed to get a reliable signal in our basic vicinity. This infuriated me, as I stared nonplussed at the pink cloud that blanketed my part of Arizona on T-Mobile's coverage map, swearing to me a solid connection could be had.
My signal is considerably better now, but it would have been nice if they had made available their Personal Coverage Check system a few years back. T-Mobile now provides an estimated coverage map down to the street level, taking the location of their cell towers into consideration to give you a better idea of what to expect where you live. Verizon has something similar, but it's not able to zoom as far, which is really the whole point to T-Mobile's bit.