A vengeful and powerful goddess that embodies the dark and destructive side of the female. Kali is often portrayed sticking out her tongue, which shows aggression. She is also often portrayed kicking some serious butt. It is important to remember that she is not a villain. Kali could send avatars out of her forehead to kill her enemies and drink their blood.
This destructive quality is part and parcel of the essence of feminity; the creator/mother is the destroyer. It's all cyclical. This feminine power is called shakti, and male gods were nothing without it, which is why they either have pronounced feminine aspects (Siva) or a constant female companion, or both.
Kali was probably the basis for the (ridiculously inaccurate - but it's just a movie, yah?) goddess religion in Indiana Jones in the The Temple of Doom. Whatever that may imply.