This popped up on reddit today. It’s apparently a little-known sub about how to listen to any radio broadcast with a $2 USB tuner. OP says we can listen to air traffic control, shortwave from around the world, the magnetic storms on Jupiter, etc.
I don’t know if it’ll be useful to us, and it’s a bit over my head, but I thought I’d pass it along, just in case. Never know, maybe someone can at least have fun with a new hobby. 
Direct link to the sub: https://www.reddit.com/r/RTLSDR
Did you too had the feeling Emily might be poltergheisting on us through some radio-station?
Apparently you can also do this with WebSDR: http://www.websdr.org
And here’s an example of HAM groups doing monitoring of signals. I like the notes like “Mysterious oscillations on 28000 kHz. I found mysterious and unstable oscillations on 28000 kHz on June 20th at 0711 utc. The direction was about 60 deg. from DL. Purpose unknown.”
this connects to the numbers station post as well (check the references there as well).