Another freebie from Amazon's Appstore, if you're out and about and looking to find the strongest Wifi signal near you to use, I'm finding this one helpful:
Wifi Analyzer
http://www.amazon.com/exec/obidos/tg...l/-/B004EBZX6W
It gives you an easy to understand graphical representation of the signals in your area, so you can see what's available and which is the strongest.