Cell Signal Strength? There's an app for that.

OpenSignalMaps is crowdsourcing locations of cell towers and their strengths using Android smartphones as probes. As more people download the app, the more valid the data will become. It is still pretty new and one of the drawbacks is that it doesn't take into account iPhone users who are not contributing to the mapping.

I entered my zip code in the program and it was very interesting to switch between the cell tower map and the heat map to see which areas were covered best by which company. Verizon, T-Mobile and Sprint had the most towers in my area while At&T had a piddly three towers. As more people contribute to this mapping, it has the possibility of becoming a very useful resource when choosing which cell company to go based on specific coverage in your area.