Software Defined Radio
SDR is dominated by windows software, so this is going to leave all that out and deal with Linux and Mac OS software.
- http://www.nws.noaa.gov/nwr/coverage/ccov.php: NOAA weather by state
- http://gqrx.dk/: GUI SDR software for macOS and Linux (including Raspberry Pi).
- https://cubicsdr.com: GUI SDR software for macOS, Linux (including Raspberry Pi), and Windows.
- Baudline: "Baudline is a time-frequency browser designed for scientific visualization of the spectral domain."
- GNU Radio: "GNU Radio is a free & open-source software development toolkit that provides signal processing blocks to implement software radios."
- Inspectrum: "inspectrum is a tool for analysing captured signals, primarily from software-defined radio receivers."