Hmm. People freaking out about these lists being too big, and here I am reading through and being surprised people here don't own more software instruments...
As for me. Start with:
imac
audio kontrol 1
running ableton live 8 suite and cubase 5...
...now add a Kurzweil k2000vx that I only use as a midi controller...
+ an APC40....
and now, the fun part (or really, the embarassing part). Name a cool softsynth/sampler/drum module --- yeah I think I have it.
...but what do I actually use regularly:
reason 4
komplete 5 - mostly use reaktor, battery, abysnth and massive
korg legacy digital + analog
g-force minimonsta, imposcar, oddity
rob papen predator
camel audio alchemy
sylenth1
microtonic + synplant
omnisphere
an average song of mine usually has 25 - 30 channels in Live, so most of all the above stuff does get used pretty regularly. the above are my absolute favorite software instruments, along with live's drum racks and operator/sampler/analog, all of which I use regularly as well.
and now, the shit I could dump and probably never miss (not because it's bad, but simply because I own too much...)
tone2 gladiator
cronoX
dimension pro
rapture (it's actually pretty cool imo...)
dsp discovery
albino3
d-cam synth squad (seems cool but...errr...no really I AM GOING to get really into this one...sooon...)
GURU (I just like drum racks for all things drummy. I don't build beats with sequencers. I build oversized kits and then bang keys).
Free Kore Player (NI's actual instruments rock, but all this kore preset stuff is just silly, over-designed, mostly useless crapage IMO...)
fabfilter twin
And don't even get me started on FX plugins...well actually it's less stuff than my synth/sampler collection, but anyway...
I just bought Trillian and now I'm DONE. Ha...ha...ha. Well it's a good new year's resolution anyway.
way too much stuff, yes. but on the upside, my album is coming out early this year, so hopefully some of my large investment will get paid back

.
I've said too much. I should just sell everything but Reaktor and Live and go from there. Hehehe. but no, I could never part with the Korg legacy collections, my favs of all...
-M
p.s. wierdly I don't own Zebra2 despite the adoration everyone has for it. tried the demo for a bit and it just didn't bite me.