Roleplaying Manuals and Worldbooks

GURPS worldbooks - some GURPS worldbooks that can be used as a source of inspiration for the Orion's Arm scenario

Extraterrestrials, A Field Guide for Earthlings - by Terence Dickinson and Adolf Schaller - a valuable source for the aspiring world builder who wishes to create his own alien species, be it intelligent or not.

The Confederation Handbook - a book review of this companion volume to Hamilton's Night's Dawn Trilogy

Worldbuilding Links - some links on the Net