Audvis - Audio Visualization is a Blender add-on for building audio visualizations. Its Real Time Analyzer drives animations that react to music or any other sound coming over the sound card or from a microphone, which the developer suggests as an option for parties. A Party Mode presents a fullscreen 3D view with no overlays or controls.
The Sequence Analyzer focuses on making music videos. Video Capture creates an image that periodically updates from a webcam picture, usable as a texture and useful in combination with the Real Time Analyzer. The Example Generator makes a grid of objects with many options.
The Shape Modifier can animate vertex location, vertex group weight, UV map, vertex color, curve radius, and grease pencil pressure or strength, across mesh, curve, surface, lattice and grease pencil objects. Drivers and Shape Modifiers can be baked for use on a render farm. A Spectrogram feature creates and updates a bakeable spectrogram image for shading, texturing or geometry nodes. It is distributed under the GPL license and listed here as free.