Build-a-Pi - Compile and Config Ham Code
Get up and running fast with a Raspberry Pi for ham radio. KM4ACK maintains and updates this script that downloads, compiles and updates several software packages that are useful to ham radio operators.
SatNOGS - Satellite Ground Station
SatNOGS is a modular and scalable stack for Satellite Ground Station implementation with rotator control, transceiver control, a machine-readable crowdsourced satellite information database and a network of ground stations.
SvxLink - EchoLink for Linux
Advanced repeater controller and EchoLink software for Linux including a GUI, Qtel - The Qt EchoLink client. NOTE: I learned about this from Tom KE5ICX when he posted about the W5FC-R EchoLink node. It's nice to know that there is an alternative to the official EchoLink software, which runs only on Windows software.