We finished watching Avatar last night and I made some offhand remark about liking Sigourney Weaver because she's such a versatile actress. And then we tried to think of other things Sigourney Weaver has been in, and could only remember Alien and Gorillas in the Mist. We also realized that Avatar is basically just what you get when you combine Alien with Gorillas in the Mist.
(Later, I remembered Heartbreakers. I still think she deserved an Oscar for that.)