RTL2832U & R820T DVB-T USB Tuner
Virtual Radar Server http://www.virtualradarserver.co.uk/
This is an application for the DVB-T tuner that I stumbled accross while using SDR#. Virtual Radar Server is an open-source application that runs a local web server. You can connect to the web server with a browser and see the positions of aircraft on a Google Maps map in real time. The software configures the DVB-T stick for 1090 MHz to receive ADS-B Automatic dependent surveillance-broadcast messages transmitted by suitably equipped aircraft.
I have this installed on a Linux (Debian) PC set up in my workshop at home. The decoded ADS-B messages can be forwarded on to an internet server for others to use however I have that feature disabled. There is a website/server in Europe called (Flightaware) that accepts feeds from all over the world. They puts a six minute delay on their data before providing flight information to the general public.