The Canary

Singing Drums Audio Plugin

Add the right tone to your drums
Make them sound crisp and full
Get that extra "punch"
Suitable for all shells in your set

The Canary may come in handy when recording and/or mixing drums. Whether your sound is missing some brilliance or has no tone, the Canary is designed to fill the gaps. The plug-in can be suitable for any shell and will enhance the attack and sustain (with parametric key/pitch knob) just as needed.

http://blackroosteraudio.com/#products

The deputy Mark II

The deputy Mark II
A synth in the tradition of classic string machines and early "polyphonic" synthesizers, written in native C++ code for high performance.

http://www.fullbucket.de/music/deputy.html

Hysteresis

If you want to create wild glitch-type effects then Glitchmachines should be your first stop. The company makes some incredible paid plug-ins but Hysteresis is one of its free offerings, combining a delay with a stutter module in an effect capable of making robotic timbres and wildly malfunctioning rhythmic patterns.

http://glitchmachines.com/downloads/hysteresis/

Hadron Particle Synthesiser

The Hadron Particle Synth is actually a hybrid of several things – as well as being a synthesizer, it’s a sampler and an effect. Like other granulator effects it breaks down sound into tiny pieces, making it ideal for creating strange vocals as well as delicate distortion. Partikkel Audio is so confident this is a leap on from granular synthesis that the company has dubbed the technology “particle synthesis”.

http://www.partikkelaudio.com/downloads/hadron-particle-synthesizer

Fracture

Fracture is another of Glitchmachines’ free effects. It works by buffering the incoming audio then sending it through a filter, three LFOs and a delay, a process capable of shaking your sounds apart. Its interface is a little less intuitive than Hysteresis, but it’s just as capable of creating hyper-detailed sounds. The fun to be had from Fracture is almost endless, but combining it with a saw wave to create massive iridescent lead sounds is probably one of the most fun things you can do with it.

http://glitchmachines.com/downloads/fracture/

Defacer

Audio Assault’s Defacer is the most metal plug-in you’re likely to find, both in name and function. It’s basically a distortion effect, but one that totally mangles any incoming audio as opposed to just making it rough around the edges, and with a few twists of the knobs you can add pretty much any sound and be given a tinnitus-inducing blast of noise. When you need to make some noise but nothing else is quite cutting it, Defacer is one to try.

http://audio-assault.com/downloads.html

Klanghem MJUC jr.

MJUC jr. is the little brother of the colorful MJUC.

It's a variable-mu** design with lots of vibe. capable of smooth leveling but also heavy pumping effects. With its two gain stages and interstage transformer simulation it offers a very deep and lively soundstage.
The three-position timing switch not only controls the attack and release times of the unit, but also the slew rate of the transformers and the timing of the other parts of the circuitry, that are directly influencing the generated harmonics (saturation).

http://klanghelm.com/MJUCjr.php

ATK Colored Compressor & Expander

ATKColoredCompressor - a compressor with a color section modulating gain around the threshold.
ATKColoredExpander - an expander with a similar color section.

http://matt.eifelle.com/2015/09/15/announcement-atkcoloredcompressor-1-0-0-and-atkcoloredexpander-1-0-0/

Big Beauty - Multi Effect

For use with guitar, but useful with any instrument
Amp channel with distortion
Effects include:

Flanger
Auto-pan
Tremelo
Delay
Wah
Reverb
EQ

Midi Learn

http://samcycle.blogspot.com.es/2011/01/big-beauty.html

YAVA 3

KRAKLI:

YAVA3 is a synth designed for big pads and weird sound effects plus rasping leads, Many thanks are owed to Dimitri Schkoda for the presets, but this synth is built for the experimenters amongst you.. Most of its power lies in the huge modulation matrix

http://www.krakli.com/krakli-free-synths/

Oxe FM Synth

Oxe FM Synth is a freeware VST 2.4 instrument plugin for Windows.

Features:
Multitimbral (16 MIDI channels);
8 operators (6 oscillators, 1 noise generator/limiter, 1 filter), all with envelope;
1 LFO per channel;
frequency modulation half-matrix with self-modulation;
global reverb and delay;
great general performance in low resources systems;
a lot of good quality patches included (thanks to Annabelle, Summa and Teksonic);
external skin support (download lcd, snow, tx802 skins by Layzer andtotolitoto’s skin by David Frappaz).

http://www.oxesoft.com/