Giant Sloths are great. Personally, I'm waiting for a comeback...
The Chupacabra was my first introduction into the wold of cryptozoology back in the day...
I am repulsed, yet drawn to the Mongolian Death Worm:
http://en.wikipedia.org/wiki/Mongolian_Death_Worm
A big red worm that supposedly haunts the deserts of Mongolia. Creepy little guy.