APRS is the abbreviation for Automatic Position Reporting System. While you can only see your position with GPS you can communicate your position with APRS. The radio amateurs worldwide have set up a network with digipeaters forwarding any APRS signal to other stations or digipeaters.
When you are using your car for example your speed, heading, altitude etc... will be transmitted. Even the ISS (International Space Station) has APRS on board. Another nice example is the diving expedition to Antartica by LX2JK where he used APRS to communicate his current location. So even at home you could see realtime what's going on.
Some amateur stations also have a weather station connected to their transmitter and can send the WX data via the APRS Network.
You can even send SMS messages to another station.
APRS is easy to install as it runs with many Packet Radio Modems.