And of course LePou and Acmebar etc are far better free guitar amp sims than Voxengo GR free etc. Music tech lists really are bollox

LePou's Cranked AC is a rocking distortion box (a sim of a Wampler AC-30 overdrive sim).  NI could do worse than to contract out GR6 to those guys.
 
Also, if you don't mind a little lo-fi weirdness, check out the one that was a finalist in last years KVR Developer's Challenge - Guitar Gadgets.