I'll start with:
Zealots = Brettonian Peasants they have that angry mob look thats what I'm using anyway.
TB line also do some nice
peasants Some of those TB line peasants might even work as Warrior priests.
This
Pendraken mini has a witch hunter look to it.
I bought some of the new
Pendraken League of Ausburg stuff to convert to witchhunters (taller hats needed

thats about all). Their new stuff is quite impressive would make some nice Dogs of War as well.
Painted pics
I have some other witchhunter stuff bookmarked somewhere I'll see if I can find it again.
A Rukh is actually a
Roc - a large bird.
A Warhammer Wood Elf warhawk would look the part with an Araby elephant howdah on it's back. I think an Eagle woud be too big for Warmaster scale. I'd go with the one with the armoured head as the others have cloth on half their head. There are some vines on the back but nothing that can't be fixed or incorporated into the design. Unfortunately you get a random one from mail order so a trip to a GW shop maybe required.

Splintered Lights
Komodo Dragons would make good sand lizards being 15mm add a hero to it's back.
GW Lizardmen jungle swarms also have some lizards but they look a bit dated now.
You could probably make Dervishers out of some of the Empire Flagellants their clothes sort of billow out.
I'll update this as I think of more.
Brutalrage we're talking about the
Warmaster Trail Armies 2009 lists, scroll down very last link.
Specifically the Witchhunters, Slayer King, Grimgor's Ardboyz and Araby Tribal and City State lists.