Always found RF to be very cool but I have a lot less experience messing around with it. With a $25 RF USB dongle though you can do some cool stuff like track the airplanes going by!
Link to USB Dongle HERE
You can use the tool Dump1090 (Link HERE) to do that!
Just git clone the link and make.
Then use the following command to start watching the planes go by!
dump1090 –interactive –net –net-beast –net-ro-port 31001
Now go to localhost:8080 in any browser to view the map!
Super cool imo!