Hello Folks, here are the ones the myself, and a few others the use the Kristal Audio Engine, have in our arsenal, and that we use a lot. All are free, and all work great! This list is lifted from my site....
Kjaerhus Audio Classic VST
http://www.kjaerhusaudio.com/classic-series.php
Luxonix LFX 1310
http://www.luxonix.com/home/en/products.html?id=lfx1310
GlaceVerb
http://www.dasample.com/index.php?show=glaceverb
Room Machine 844
http://www.silverspike.com/?Products:RoomMachine_844
Anwida Soft DX Reverb Lite
http://www.anwida.com/
Deep Sound VST Packs
http://mp3.deepsound.net/plugins_packs.php
Elogoxa
http://www.uv.es/~ruizcan/p_vst.htm
S.I.R_Super Impuls Reverb
http://www.knufinke.de/sir/index_en.html
Voxengo
http://www.voxengo.com/
Strip Tool
http://www.vb-audio.com/
MDA
http://www.mda-vst.com/
GVST
http://www.gvst.co.uk/index.htm
Gersic
http://www.gersic.com/plugins/index.php?daCat=-3
Free Amp
http://www.frettedsynth.com/
The best free amp modeler I have found, but it is resource hungry!
Deep Sound
http://mp3.deepsound.net/plugins_packs.php
LOTS of VST's on here, this site will keep ya busy! A must have is the Paris Parametric EQ, it is my favorite plugin, period.
Don't Crack.com
http://www.dontcrack.com/freeware/
The best site that I have found that has free stuff for both PC AND Macs.
NCH Swift Sound
http://www.nch.com.au/
Not really a site of VST's, but there free audio software works quite well.
Enjoy!!