First off, I would recommend getting the most recent digital copy of CM magazine. There's about 80 some plugins you get with it, all either full versions or slightly cut down version of the full retail. Also a bunch of sample packs, tutorials, etc...
After that, the list can be pretty big, knowing there are thousands of plugins available for free in VST format.
A few of the top of my head :
instruments :
TickyClav 2 (2getheraudio)
AGML2 (Ample Sound)
FB3100, FB3200, FB3300, scrooo, ..., ... (Full Bucket Music)
Kairatune (Futucraft)
Martinic Kee Bass (Martinic)
SQ8rom (SampleScience)
Lord of the Springs (Taron)
Podolski, TripleCheese, TyrellN6, ... (U-He)
effects:
Multiply (Acon Digital)
Leveling Tool (AdHD)
Camel Crusher (Camel Audio)
FreqShifter, ..., ... (Full Bucket Music)
Gvst bundle (Gvst)
Meldaproduction bundle (Melda Production)
HY-delay4 free (HY-plugins)
CONVOLOGY XT (Impulse Record) => this is only the best 'free' impulse response reverb tool ever

iZotope vinyl, Imager, ... (iZotope)
MJUC free, ..., ... (Klanghelm plugins)
Frohmage (Ohm Force)
Tal-DUB I, II and III, TAL-flanger, TAL-bitcrush, ..., ... (TAL freebies)
mvMeter2 (TBpro Audio)
Kotelnikov, Nova, SlickEQ, ... (Tokyo Dawn Labs)
FreqEcho (Valhalla Plugins)
Span, Correlometer, ..., ... (Voxengo)
The list goes on and on and on though.....
...and on...