I want to highlight a few VST instruments and effects I have been using lately, and I'll limit the list to those available for free download. The developers all deserve big thanks for writing great software and sharing it.

Orca from FXPansion
This odd looking soft-synth sounds great with warm, rich tones, and it only has four knobs. IMHO four is about the maximum number of knobs any synth should have. Many other nerds would disagree, but I prefer four knobs that make big changes in the sound, rather than dozens of knobs that make small changes. I like tweaking knobs as much as the next producer, but I'd rather be spending time working on the groove.
Orca download page

dmiHammer from Smart Electronix
This little synth basically makes one type of sound, but once again I like the tone, and it has come in handy a few times. I like having dozens of little specialized synths at my disposable, rather than one monster synth that purports to do everything.
dmiHammer download page

I guess I've outed myself as a Cubase user. I've got nothing against Logic, but my hackles were slightly raised the other day when another producer referred to Cubase as "the dark side." I mean, c'mon, all music software is made by nerdy German guys who want to make life easy for music producers, right? (joke ... the all German thing, but they do seem to be a majority for some reason). I like Cubase for its openness. Umberto Eco once wrote a column comparing the Mac to Catholicism and the PC to Protestantism. In the same vein, Logic seems to be more Catholic, and Cubase more Protestant. I use Cubase on a Mac, so I guess I am ecumenical.

Harmonical from ndc plugs
This is really a weird one. I've only actually used it in a few tracks, but I give it a try in almost everything because it is so fun, and the sounds are unusual. I'm not a math whiz so I have no idea what spherical harmonics are, but they sound buzzy and complex.
Download Harmonical

Download and enjoy. I found these gems and many others at KVR Audio, a great site with an extremely useful search engine for music software.

Hmmm ... after re-reading the Umberto Eco essay I may have to reverse my stance on if Cubase is more Catholic or more Protestant. I'm not a true dual user ... if you are I invite you to chime in.