Native Instruments Kontakt Player
Platform/format: PC, Mac/VST, AU, RTAS Download
We can't see many people turning their noses up at this one: it's a sample playback instrument based on Kontakt 3.5, so features much of that software's technology. It can load all current and previous Kontakt libraries, and to get you started, there's also the free Kontakt Factory Selection, which contains 50 instruments.
Russell Stoneback Light Guitar
Platform/format: Mac/AU Download
We didn't even know what the Light Guitar was, never mind that there's a software version, but it turns out that both the hardware and software come from the same stable. The real instrument turns light into sound (click here for an explanation) while the virtual edition emulates its behaviour in a plug-in.
Sonic Lion Lion Chorus
Platform/format: PC/VST Download
LionChorus has been ripped from Sonic Lion's Nitrox synth, and is designed to offer classic chorus/flanging effects. To this end, it has four stages and a feedback line with high-pass filter. The plug-in is actually donationware, so put some money in the hat if you're going to keep using it.