Here some starters - this is what I have in my “Free for live” folder (pasting all the links is a bit tedious, but Google is your friend):
- Allround sets: BlueCat freeware pack, GVST suite, Melda Audio free plugins, ReaPlugs (Reaper plugins as standalone), some of the Airwindows plugs are pretty neat, too
- Amp Plugins: Poulin amp simulators, Mercuriall Cab, Voxengo Boogex
- Arpeggiators: Arto Vaarala Kirnu, RandARP
- Compression: Klanghelm DC1A2, TDR Kotelnikov
- Delay: DD-Delay, TAL-Dub 2, Valhalla FreqEcho, Voxengo TempoDelay
- Equalizer: TDR VOS SlickEQ, TDR Nova, Mellowmuse EQ1A
- Guitar Stompboxes: all Distorque (FaceBender, PlusDistortion, Rangebastard, Vitamin C), Mercuriall GreedSmasher, TSE R47 and 808
- Modulation: TAL Chorus LX, Distorque Azurite Chorus, Pecheneg Tremolo, Adam Szabo Phazor, Acon Multiply
- Reverb: Sanford Reverb - but really DO get Valhalla VintageVerb; not free but cheap and GREAT
- Sampler: TX16Wx and Grace (by One Small Clue)
- Synths: Tyrell N6, PG-8x, Monofury are my favorites, but also worth mentioning are Charlatan 2.0, Deputy Mark II, TAL NoiseMaker, Nabla and Ragnarok
Another cool free plugin if you’re into looping (or want to try your hand): Mobius by Circular Labs
Hope this gives you something useful to play with!
Cheers,
Torsten