We don't often think of sci-fi geeks as the manliest of men, but they need their man caves, too. Like most man caves, the nerd sanctuary is a place to show off collections and memorabilia that might not necessarily be welcome elsewhere the house. It can certainly (and does usually) feature a big-screen TV. But in other ways, the geek cave is a little different from the rest. The focal point here isn't the bar, it's the stuff: think shrink-wrapped first-edition comic books and X-Men figurines in their original packaging. And the TV is for "Star Trek," not the Super Bowl.
Must-have: The aforementioned geek collections, and a souped-up computer.