WOK has released RackTube, a tube effect VST plug-in for Windows PC.
This is a simple tube-emulator, giving some saturation (or distortion) to your audio. Use it as an insert on single tracks or master. Not much more to say to this one, just try it out.
RackTube is available as donationware. A free version with a nagscreen can be downloaded from the product page.
Visit WOK for more information.