Free dynamic equalizer from Tokyio Dawn.
Frequency selective compression
Goodhertz are offering a free and good stereo tool:
Midside Matrix pares down our acclaimed mid/side processor, Midside, to just the essentials: mid/side matrixing, gains, monitoring, & metering — all in a simple, lightweight package.
StereoTool offers ultra-precise control of input gain and individual pan for left and right channels, accurate visual feedback reflecting the signal content with; a vector scope, PPM meters for inputs/outputs, phase correlation meter permanently monitoring the signal and individual left and right polarity reversal – No dongle or registration required – 100% Freeware!
Chris from Airwindows develops quality audio plugins and gives them away for free (Recommend to donate if you´ll use these a lot). He focuses on the sound quality and leaves the UIs simple and raw.
Every plugin comes with a video to it, like this one:
HOFA offers a buch of free audio tools for free including :
Meter, Fader & MS-Pan
Goniometer & Korrelator