Wahman is a free audio plugin, wah-wah stomp emulation, based on real scheme.

Features
- 64-bit internal processing
- input level adjustment
- mono/stereo processing

http://www.nsp-vst.ru

BlackBooster

BlackBooster is a free audio plugin for Microsoft Windows, booster stomp emulation, based on real scheme.

- 64-bit internal processing
- input level adjustment
- mono/stereo processing

www.nsp-vst.ru

modulatedFilter

modulatedFilter is a modulated filter with one LFO. Can modulate filter frequency, band width and filter mix! Extremely low resources taken!

Features:
One filter width lowpass, highpass and bandpass
Band width and filter mix
One LFO working synchronously host with start position of oscillating.
LFO can modulate filter frequency, band width and filter mix.

http://vst.saschart.com/modulatedfilter

SIR spectrum analyzer

SpectrumAnalyzer is a state-of-the-art spectrum analyzer plugin, which offers a lot of opportunities to display the spectral content of your audio material and helps you create a better mix this way. SpectrumAnalyzer comes in two editions, a free and a full version.
SpectrumAnalyzer uses modern and reliable technics to analyze your audio material. It has a FFT (Fast-Fourier-Transform) and an analog-style (parallel band-pass IIR filter) engine, both of which can run simultaneously. So you can benefit from the more accurate time resolution of the band-pass filters and the better frequency resolution of the FFT at the same time. Check out the cool intelligent peak-detection, which automatically detects resonant frequency peaks in the signal. Use the snapshot function to easily save the current state of your analyzer, so you can compare the spectral profile of your current project with other songs. SpectrumAnalyzer also includes a VU-Meter (with peak and RMS measurement) and a Stereo Correlation Meter.

http://www.siraudiotools.com/Spectrum-Analyzer.php

HY-Filter2

It’s multi mode filter effect.
There are both free/commercial version.
Free version has 2 filter modes(multi filter, reso filter),
commercial version has 7 filter modes(multi, reso, step, bank, stereo, gate).

http://hyakken.moo.jp/WordPress/product/hy-filter2/

Filterjam

Filterjam is a multi-band resonant filter delivering weird ringmod-like filtered sounds. The input signal is divided into 4 bands that are then summed or multiplied together according to the selected mode. Filterjam can be very harsh or gentle, it can add brightness or depth to synth sounds, but it can also completely mangle acoustic sources.

https://www.audiothing.net/effects/filterjam/

Airwindows various

Airwindows plugins are modular, graphic-less, stripped-down, VST plugins.

why no GUI?

Airwindows’ reputation was built out of generic-interface plugins, which typically focus on doing only one thing, often with very simple controls, labelled to help understanding but not to encourage formulaic work. There are two reasons for the generic, non-GUI interfaces. One, because it improves reliability a huge amount (many audio plugin bugs, including showstopper bugs, have to do with the GUI part). Two, because time that could be spent debugging the GUI or tweaking its look—or writing copyprotect code—can be better spent improving the sound. That’s how Airwindows rolls, since 2007.

in mix, nobody can hear your screen

Airwindows is about listening. It’s about the sound being far more exciting than looking at the screen, because that’s all your audience will have to go by. If you get good feelings, it had better be about what you hear! The plugins naturally lend themselves to MIDI control, assigning sliders to control surfaces. Doing that, you can mix without watching pixels, and listen without being distracted by nonsounds.

PurestGain, Distance, SurgeTide, Point, ToneSlant...

http://www.airwindows.com/category/free/

X Crash

X Crash is a sampled 16 inch crash cymbal. This is an "explosive" crash from a well known cymbal maker. It was recorded using 3 microphones (one aiming at the top + a stereo pair to capture the room sound). You can mix the 2 tracks using different settings to sculpt its sound and get a wide sonic range.

Samples were carefully edited and chosen, they are long, from 18 to 20 seconds, and are organized on 4 velocity layers to get a natural sound and play.

http://www.vst4free.com/free_vst.php?plugin=X_Crash&id=2562

Sanford Cobalt synthesizer

Sanford Sound Design has set free its Cobalt synthesizer inspired by many of the digital synthesizers from the 1980s.

In the early 80s as digital technology became cheaper, many manufacturers designed synthesizers that combined earlier analog technology with newer digital technology. These were known as hybrid synthesizers. Well-known hybrid synthesizers are the Korg DW8000 and DW6000, the Ensoniq ESQ-1, and the Kawai K3.

In analog/digital hybrid synthesizers, the oscillators responsible for generating waveforms are digital while the filter section remains analog. This approach freed designers to use any kind of waveform; they were no longer restricted to traditional analog waveforms such as sawtooth, triangle, and pulse. However, by using an analog filter, these synthesizers retained the warmth earlier analog synthesizers were known for.

Though Cobalt is a purely digital synthesizer, its overall architecture is very much like those early hybrid synthesizers. It features a wide selection of waveforms, most of which were resynthesized from actual hybrid synthesizers, while providing traditional subtractive synthesis capabilities for sculpting its sound.

http://www.lesliesanford.com/vst/plugins/

Xfer Pump compressor

Xfer Records OTT is a free re-creation of a popular aggressive multiband upwards/downwards compressor set-up used by many dubstep and electro producers.

https://splice.com/plugins/3788-ott-vst-au-by-xfer-records

PanENV

panENV can position the output anywhere from left to right. Use envelope from midi input with attack, hold, and decay. Extremely low resources taken!  Enhance your stereo signal!

Features:
Pan out from left to right with pan offset.
Envelope from midi input with attack, hold, and decay.
Pan width for stereo enhanced.
Pan offset to play around.
Enhance volume in sides for nice effects.
Few envelope shapes.
Persistent envelope after note off.

http://vst.saschart.com/panenv

Archetype Instruments Lokomotiv

Another out-and-out dance-type synth, Locamotiv might not be that pretty –it’s pretty dark and just black and white – but has a fat sound. It has some fantastic basses and leads, and is ultra clean and perfect for today’s electronic music producer.

http://www.kvraudio.com/product/lokomotiv-by-archetype-instruments

Kairatune

Kairatune is designed to produce crisp and tight electric sounds for electronic music production. Kairatune is engineered for the demanding producer who needs to push the sound to extremes without compromising audio quality.
Kairatune is not your all-in-one synthesizer. It’s designed and engineered to be as powerful and versatile as possible in it’s target role as your source for tight bass, unique lead and shiny SFX sounds.

http://futucraft.com/kairatune/