These links are either currently maintained and active, or useful static resources (although they may have been last maintained some time ago).
Both the main books are out of print, but watermarked pdfs can be obtained through DriveThruRPG.
Lords of Gossamer and Shadow – a variation on Amber
With further Amber publications stalled, a variant on the system was launched. You can read more about it here:
You Should Be Playing Lords of Gossamer and Shadow
Lords of Gossamer and Shadow – Rite Publishing