pgnotifyd connects to a PostgreSQL database, listening for the named asynchronous notification. When notification is received, it executes the given command. It can work as a drop-in replacement for polling a PostgreSQL database for changes (e.g., using crontab(5)), and is typically a cleaner and more efficient alternative.
trx is a toolset for broadcasting live audio from Linux. It sends and receives encoded audio over IP networks, via a soundcard or audio interface, and can be used for point-to-point audio links or multicast (e.g., private transmitter links or audio distribution). High-quality wideband audio (such as music) can be sent with low latency and fast recovery from dropouts.
xwax allows DJs and turntablists to playback digital audio files controlled using normal turntables via timecoded vinyl. It handles needle drops, pitch changes, scratching, spinbacks, and rewinds, making it a capable tool for beat-mixing and scratch-mixing. It focuses on an accurate vinyl feel that is efficient, stable, and fast.