Web SDR Receivers
The possibility of using a Wide-band Web SDRs (Software-Defined Radios) to just tune in on a frequency and listen to the waves washing over the world feels very cyberfopsy🦊.
There are various Web SDR recievers out there that can just be used freely, such as http://websdr.ewi.utwente.nl:8901/ and http://appr.org.br:8901/.