It is cool to do. But there are professional uses for it, particularly like finding interference or noise. You can ask things like: "How crowded is my 2.4 GHz spectrum?"
The RTL SDR is the gateway drug into SDR's. The bandwidth is limited, so don't expect to be capturing HDTV Streams. But it's certainly possible to listen to AM/FM, Ham Bands, VHF/UHF signals, etc.
If you don't want to buy an RTL-SDR, you can search KiwiSDR which is a streaming SDR for frequencies under 30MHz. You can also connect to KiwiSDR's worldwide.
Then if you get the itch, you can go get your a HackRF, a ham license, or whatever else scratches it.
The RTL SDR is the gateway drug into SDR's. The bandwidth is limited, so don't expect to be capturing HDTV Streams. But it's certainly possible to listen to AM/FM, Ham Bands, VHF/UHF signals, etc.
If you don't want to buy an RTL-SDR, you can search KiwiSDR which is a streaming SDR for frequencies under 30MHz. You can also connect to KiwiSDR's worldwide.
Then if you get the itch, you can go get your a HackRF, a ham license, or whatever else scratches it.