Greenskins, yes - though right now my main problem is making an appropriate skeleton / base orc mesh
I really like the Night Goblins and Black Orcs, and while making the armour for the greenskins isn't a problem, it's the base model that I'm challenged by - since I'll need to build one from scratch (which takes a
long time on MdlVis, since it's one polygon at a time for each triangle, with hundreds of triangles per model)
Beastmen, probably not, certainly none of the bigger creatures
The tricky part about Beastmen is they need seamless skins.
Combine that with the tricky mesh of goat-men and the more bestial/violent animations, and it's certainly a learning experience.
Presently, the closest violently animated model I have is the Uruk Warrior 2.1 (unreleased) with pushing, shoving, howling, head shaking, and weapon clashing/shield bashing.
Modeling this fellow at the time of writing this