Ok i dont know if there is à thread like this .
But à search for free vst is not working so i belive this should be sticky.
Post your favorit pluggin using The example below.
Pluggin name
Developer
Vst effect , vsti or other
What kind of pluggin (ex: compressor)
32bit, 64bit or 32/64bit
Link to The pluggin page
Some info on why u like The pluggin.
Rather than write them all out I’ll just say 3 good places to start looking are Togu Audio Line, U-He & Variety of Sound.
Togu Audio Line for a whole range of effects, EQs & softsynths:
http://kunz.corrupt.ch/products
U-He for softsynths:
Variety of Sound for EQs, compressors, saturation, effects & even channels strips:
EDIT
Other quality freeware mixing plug-ins that I find invaluable:
Tone Projects Basslane, monos everything below your selected frequency to add punch & power, if it doesn’t you’ve probably got phase issues:
Flux Stereo Tool, for checking phase and even stereo widening/fixing:
Brainworx Solo & Cleansweep, for easy mid/side & quick hi/low pass eq:
http://www.brainworx-music.de/en/plugins
Elysia Niveau Filter, tasty tilt eq:
TT Dynamic Range Meter, check your loudness - also has handy a mono button:
http://www.dynamicrangemetering.com/
Sonalksis Free G, handy fader if you need to run hot into a plug-in to get the best effect out of it then trim afterwards to keep your gain-staging:
…aaand finally Voxengo Span, spectrum analyser (and other plugs):
Oh, I forgot the S(m)exoscope!
http://bram.smartelectronix.com/plugins.php?id=4
Useful for checking how your compressor/limiter/clipper is adding body whilst taming those peaks 
For free, you have to look at the mighty Greenoak Crystal soft-synth.
http://www.greenoak.com/crystal/indexDesktop.html
Neil.
You can join the mighty KvR community.
They have nearly every little thing in the database which has to do with VST technology.
Another large “go grab them now” vote for Bootsy’s stuff at Variety Of Sound.
They are donationware, but better than a lot of paid stuff to my ears.
Love his BootEQ MkII.
+1 vor Bootsie’s stuff.
From my side I’m in love with NastyDLA.
All the internal effects of cubase ?? 