GD's Warhammer Archaeology Blog
This has a great link to an article all about GW's creation of Fimir - extremely interesting read!
Fimir and Zoats are interesting, and a pity they have not taken off and commanded attention the way beholders did, using the example of "unique monster found in this game universe only, not a pastiche of others'", though the beholder is an easier meme (eye tyrant etc.).
Warpstone's Fimir issue is a good read though yes, they are also a very "adult content" race at their core. After what a certain crowd did with attacks on the roleplay hobby over Type IV demons etc. in D&D, one can only shudder to think what they would have done with Fimir.
Hm, my players may wander through a swamp soon...