Madtracker- VST-Plugins (list taken from the madtracker forum)

last change June 12th, 2004
Some tips:
  Axxeom Keyboard to Midi keyboard convertor!
  Bioroid Scratch your samples!
FFX4 VST effect to host DirectX plugins (this *so* rules!)
  MP3PLAY VST effect to host .mp3 files!
  Phat VST effect to host .rex files!
SFZ VST instrument that lets you play soundfonts, now reads .ogg files too!

Free VST plugins (instruments)
  Ace-music-exp Very, er, colourful effects and instruments (plugins can be found in the 'download' section)
Andreas Ersson VSTi plugins softsynths and drumsynths, checkout IBlit a great sounding monophone synth with very low cpu usage
Audionerdz Delay Lama The Virtual Singing Monk, its great fun to play around with!
Buzzroom's Lallapallooza Lite This is a great synth for trance music!
Buzzroom's BB303i The basses that come out of this plugin are really phat!
Camelaudio`s Cameleon5000 well not really free plugin but well worth a try!
ConcreteFX / Ensembler very nice string ensemble sounds
  D-Animator's Quacker nice and easy bass synth with low cpu use
  ElogoXa free VST plugins effects and instruments
E-phonic E-Phonic effects and instruments, checkout Drumatic 2 a high quality drumsynth
  EVM / Grandpiano 10 MB sample module with some adjusting features (delay,sustain)
EVM / Isotope interesting synt with great sound
  EVM / Maelstrom Interesting synt plugin with nice sound which can be used for pads and warm sounds at low cpu usage.
  FXPansion / DR005 Free drumsampler with 16 channels
Green Oak Crystal VSTi has some amazing basses
  Klangformer VST Klangformer VST instruments (nice ones!)
Krakli Krakli instruments, sometimes weird sounding plugins, checkout EzPoly!
Linplug Free Alpha VSTi Very useful and easy softsynth
Magnus (Smartelectronix) effects Drumatic drum synthsizer,Invader FX synthesizer,LOFI cool effect, checkout Ambience!
mda-vst MDA VST effects (click 'vst effects') and synths ('vst synths') very nice collection of VSTs, be sure to checkout mda-piano!
Microsynth VSTi by Chris Huelsbeck the famous musician of the 8-Bit times. It is a very good emulation of the SID soundchip of the C64!
Muon Tau included in the VSTi-collection is the free Tau bassline. Nice 303 like bassline, low cpu use.
Novaflash / Snip this synth bleeps and sounds really liquid, great sound quality
OdO-Synths great instruments to checkout: Dreamer , A-Pad , Psydrums
ReFX CLAW 303 emu with 18dB/octave filters nice sound by low cpu use
RGC:audio RGC-Audio`s Triangle I and Triangle II and the great soundfontplayer SFZ
Rumpelrausch Täips ZR-3 a great and very authentic organ vsti, if you are a fan of those old 60s sounds
  Sampletank 1 Free Sampletank 1 instrument plugin
Soundfonts.it's ORGANized a very nice and warm sounding organ
Stefan Kuhn has great VSTi`s checkout Ganymed, Vivaldi and VivaldiMX !
  Super Destroy FX (DFX) plugins (instruments and effects)
SuperWave P8 VSTi top notch vsti especially for heavy detuned trance synths!
Synth 1 VSTi very nice allround synt with low cpu-usage, get the extra-soundpack too!
  Ticky Clav VSTi Hohner Clavinet emulator
Ymvst ymVST Atari ST chipsound instrument

Free VST plugins (effects)
  Ace-music-exp Very, er, colourful effects and instruments (plugins can be found in the 'download' section)
  Bojo Bojo effects
Bram (Smartelectronix) effects ---
Buzzroom / BigCheese (Tremolo+Filter) the easiest way to produce tremolos for chilling sounds
  Digitalfishphones VSTe by one of the programmers of Magix
  Dunk / Scrubber create those typical time stretched jungle sounds
  Elemental Audio / Inspector Very nice and free analyzer , very useful
  ElogoXa free VST plugins effects and instruments
Exponent Deltaforce Great distortion plugin for bass sounds in drum n bass
E-phonic E-Phonic effects and instruments, checkout Drumatic 2 a high quality drumsynth
  FxFreeze no more frozen apps
  Interruptor / Echomania creates very complex echoes
  Ismusic Basic effects / Slim slow slider
Kjaerhus plugins for basic effects, checkout the classic series, good and easy to handle vst effects!
Krakli Krakli instruments, sometimes weird sounding plugins, checkout EzPoly!
Linplug Free Alpha VSTi Very useful and easy softsynth
Magnus (Smartelectronix) effects Drumatic drum synthsizer,Invader FX synthesizer,LOFI cool effect, checkout Ambience!
mda-vst MDA VST effects (click 'vst effects') and synths ('vst synths') very nice collection of VSTs, be sure to checkout mda-piano!
NDC-Plugs / The Modulator (Pitch,FM,ringmod) very versatile and well designed modulator includes the mad-shifta routine for pitching
  Novaflash / Twister nice effect to mangle your samples, weird flanger settings possible
  Ohmforce Frohmage filter Ohmforce Frohmage filter
  OtiumFX Basslane Nice plugin to enhance bass sounds
Paris VST EQ Paris VST EQ is a very versatile and nicely designed EQ
  Prosoniq Northpole filter plugin via 'download' -> 'freebies'
PSP Pianoverb Reverb plugin for string based instrument, sounds great on piano vsti's!
  Silver Spikes TapeIt free wave out (note: its like hitting record on your sound software, you wont get the high quality madtracker offers for pro registered users)
Silver Spikes RoomMachine844 very nice reverb plugin especially good for tight short reverbs
  Sinusweb VST effects (one free, the others shareware without real limitations)
Smartelectronix plugins ---
  Super Destroy FX (DFX) plugins (instruments and effects)
TBT / TapeStop It simulates the sound when you turn off a tape or turntable!
TLS Soundmaximizer very nice and easy to use master sound maximizer / limiter
  Tobybear Todybear's free and shareware effects checkout DC-Killer and Mad Shifta!
  VB-Audio VB-audio effects (go to 'demos' for downloads)
VOXENGO`s SPAN (spectrum analyzer) a very nice and useful spectrum analyzer for free!

Databases of VST plugins (free and shareware)
http://moritz-sounds.de.vu/ It gives an overview of free VST plugins, including screenshots, descriptions, and downloadlinks. Ideal for those who are searching for something specific.
KVR-VST Probably the biggest and most comprehensive database of all VST plugins (both free as paid)
  Crmav plugins database plugin database
  Acidfreak Freeware & shareware VST overview
  Database Audio freeware resources for electronic musicians
  Vstcentral Comprehensive database of VST and DX plugins
  Audioattack.de German database of free VST plugins

links marked with a star are my personal favourites