I wish that I could afford the AV 20/ 10 Marks from Deutsches Neu Guinea in MS! Here is my Walia Ibex from Ethiopia/ thank God that I was able to afford the 24 Country Conservation Series in Gold/ Silver!
Of course "unusual" is vague, but I assume you mean besides the usual lions, elephants, bears, etc. Here's some you don't see so often.
The Eurasian Elk (Alces alces) is now considered a different species from the American and East Siberian Moose.
Some of my favorite notgeld pieces: I'm not sure (since I'm away from home) if I still have the third one - had two, sold one to another CT forum member a while back. I think this is the one I kept...