Space Elevators: How a sci-fi dream could be built today
Surveying the current practical and theoretical factors for and against space elevators (including partial elevators—skyhooks!).
Project Orbital Ring
An Orbital Ring System as an alternative to a space elevator.
Representing nothing short of the most ambitious project in the history of space exploration and exploitation, the Orbital Ring System is more or less what you would imagine it to be, a gargantuan metal ring high above the Earth, spanning the length of its 40,000 kilometer-long diameter.
Related links
Project Icarus
A joint effort by the Tau Zero Foundation and the British Interplanetary Society to research the design of an interstellar spacecraft.