I'm afraid I can't find the (non-LO) blog where I saw this idea a while ago, but the old Skaven clanrats - or current night runners - while not very ratty actually make quite a decent base for some kind of stunted and deformed humans. Here's an example:
This isn't the point of my post though. I had a bunch of the old 2nd edition Gretchin lying around - I'd actually been trying (unsuccessfully) to sell them when I realised that they're actually pretty similar in size. Again, I had seen people update these models with head swaps (either Goblin heads for Grotz or Cadian heads for Squats) and I realised that I could do something similar:
Just a simple head swap and one or two other minor conversions scattered throughout (every model has a head swap and one other change). As I say, these are about the same size as the Skaven-based models:
And here I some that I painted - nothing too fancy, since they're still not the greatest models, but it's easy enough to knock out a small horde:
Despite having to convert every single one, I really found that they were surprisingly quick because of the one-piece base model (no separate arms, legs, etc here). They were also practically free, since I had the bitz lying around with no real other use anyway. Now I just need to find an excuse to field loads of autogun-armed scavvies... Perhaps I'll find use for them as Nurgle Cultists (40k).