Slate has an awesome article on the end of the universe, in which the author interviews several cosmologists, trying to find out how it will happen and how humanity might survive. (Bottom line: no one really knows.)
Here's a bit I quite liked, regarding the future of intelligent life in an ever colder universe:
"The most plausible answer," Dyson said, "is that conscious life will take the form of interstellar dust clouds." He was alluding to the kind of inorganic life forms imagined by the late astronomer Sir Fred Hoyle in his 1957 science fiction novel, The Black Cloud. "An ever-expanding network of charged dust particles, communicating by electromagnetic forces, has all the complexity necessary for thinking an infinite number of novel thoughts."
How, I objected, can we really imagine such a wispy thing, spread out over billions of light-years of space, being conscious?
"Well," he said, "how do you imagine a couple of kilograms of protoplasm in someone's skull being conscious? We have no idea how that works either."