One of the more interesting and practical uses of Twitter (a mobile phone text message service that allows you to connect with other users) is instant updates during emergency situations. Right now at this moment, as fires rage across southern California, you can get up to the moment information on the latest both from individuals and from local news organizations like KPBS in San Diego.
These kind of tools are particularly useful and important when landline phone and even cell services become congested and unusable, and may indeed save lives.