It's been brought to my attention that 11 years ago, an architect made a mad plan to give us more space. To be specific, seven Earths of space, using the materials of the earth itself. Just one problem -- the original earth would be completely destroyed.
Specifically, the plan was to drill into four spots in the equator, and have it pumped up four space elevators, producing an ever-growing ring around the earth, which would be expanded over time into a giant hollow shell. As this worked, the sky would darken, gravity would shrink (due to more of the earth being above you than below you), and everything would slowly get moved up. Halfway through the process, all of our nature and civilization would have to be moved up to the hollow surface up top. Finally, the shriveled up earth collapses, raining down on the inner surface, providing it with the atmosphere and water it needs to survive.
Other engineers have pointed out just a minor rub in the plan. Namely, the nickle-iron substance of the mantle that he was planning to use as the primary framework could not withstand the strain of an object that big, and would collapse. With some slight reenforcement from asteroid-iron, it could survive that, only to get ripped apart by the lunar and solar tides. Ultimately, a stable lattice would require materials that have not yet been invented.
It's clear to me that eventually, we will need more space than the earth has. Every idea, even the completely crazy ones, will help.