Echoecho is one of the most useful location-based apps on the market today. When you hear the word “location-based app,” chances are you are thinking about services like Foursquare and Gowalla. While these can be fun, their utility is rather limited (unless you really feel the need to collect virtual badges). Echoecho, on the other hand, was built from the ground up to solve a simple problem: finding where your friends are. The service lets you ask your friends where they are and then decide on a place to meet up if you feel like doing so.