Castround isn't the only geographically specific Twitter app, but it is one that's easy to use and has lots of features. It could be a handy tool to have at your side.
At its core, Castround is quite simple. You log in with your Twitter account and tell the app the epicentre of a geographical area you are interested in. Then you identify a circle around that area using a slider to increase and decrease the size of the circle. Now you are ready to view tweets – plus you can create more than one location and save these as favourites with familiar names. To help you filter through all the tweets Castround will identify topics and trending tags and you can set keywords to look for in tweets.
Castround might not be something you will use every day, but it could be really handy at times. Suppose you are visiting an event and want to keep an eye on what other people are saying about it. Suppose you are looking at some breaking news and want to pick up real people's voices in real time. Suppose you are stuck in traffic – use your current location to create a Castround circle, and view tweets to find out why.