I've never painted any beastmen before, but I've always liked the concept of them. They're the rural equivalent of the skaven: while the skaven are plague and urban squalor personified, the beastmen represent the brutal, violent side of nature, always looking for hapless peasants to batter and kill.
I found some plastic 40k beastmen from the game Blackstone Fortress on ebay. They're quite recent models, and are very nice sculpts. They come in pieces, so you can introduce a little bit of variation by swapping their faces around. They've got slightly less bestial faces than the Warhammer beastmen, but still look as if they've come straight from the island of Doctor Moreau, and aren't happy about it.
I did some conversions to make them suitable for Mordheim. This involved cutting off their pistols and some grenades from their belts. I sculpted a rag over the former grenades on one of the beastmen. The other one (the one with running legs) had more mess to cover. Luckily, I had a metal plate taken from a plastic ogre which fitted really well. I stuck that on and painted them. The standing guy got stripey trousers, which he probably stole from some unfortunate treasure-hunter. Their decrepit shields - also probably stolen - were taken from some old plastic skeletons. the running bloke got a new sword, also from the skeleton frame.
Next up is a metal Privateer Press model. This isn't the cheapest miniature I've ever bought off ebay, but it's close: it cost me the king's ransom of £2, and had some slight damage to the bow protruding over its shoulder. This guy is Victor Pendrake, a sort of travelling scholar/monster hunter. His combination of cloak/coat and armour reminds me of the Mordheim witch hunters. There's lots of nice detail on the model, especially given that it's quite old and from a period when Privateer Press sculpts could be quite ropey: he's got books in his pockets and little spectacles on his face.
I found that it was too easy to paint him in shades of brown and metal, so his coat got a red lining and his armour had a blue wash for variety. I really like the way that he's got his boot up on what looks like a beastman's head. I repaired the top of his bow with - oddly - a spare Eldar shuriken catapult magazine. He reminds me of a cross between Blade and the Witcher, which seems appropriate.