Signalmap is a neat webapp that lets you punch in your zip code and your cellphone provider and see how the reception is where you live. Not only can you use it to gauge where the best place is to make your call, you can compare the four big providers so you can see which one is best suited for you (based on your home and work location). Of course, the signals are all user-contributed, so there's no guarantee that providers themselves haven't gone and flooded the site with slightly higher than usual signal ratings. [Signalmap]