I've had some of these ugly little fellows since I was in primary school. A couple of years back, I based them on pennies for our 15mm RPG campaign.
They work pretty well at that scale as gnolls or Gloranthan dark trolls. Nick Lund's creations tend to be quite tough and aggressive-looking regardless of size, so they might actually work best as big, burly beasties in 15mm.
The big one, Gnar, is supposedly a 'mutant goblin' - or at least that's how he was described on box of Eeza Ugezod's Death Commandos. But he's very clearly a kobold.
These were very quick to paint. I was playing around with Citadel's Nighthaunt Gloom on the skin; one coat of that and then just a few dabs of Vallejo silver grey to highlight. Nighthaunt Gloom was apparently a prototype of the new and much-hyped contrast paints. I was pleased with how it worked - it gave much better shading, etc., than a normal wash.
These are rather different from my other kobolds, so I saw no point in attempting to match them up colour-wise. They're also singularly lacking in missile weapons, though I do have a wizard for them (indeed, several: he's one of those miniatures that crops up all the time in eBay job lots). I'll have to get him painted up shortly.