-- Houston Electronically
Gathered GURPS Alliance
World-Making:
- World Wrights' Web,
- More texts on world-building, by Juha juuso Vesanto (including useful spreadsheets),
- Contact: they build a new world every year!
- Encyclopedia Mythica: a nice resource.
- Sacred Woods and the Lore of Trees,
- Medieval price list
Language Creation
- Language Construction Kit,
- Online phonology course,
- SAMPA Computer Readable ASCII Phonetic Alphabet,
- Model Languages home page,
- Chris Pound's Perl scripts for word creation.
by 
- Errata and an index for the game,
- A List of recommended reading,
- Lots of information about Emperor of the United States Norton I.
- Phil Masters' steampunk resources.
by
- All these are now available over on the HEGGA Links page.
,
created by 
- Heliograph: cullings from the Space:1889 mailing list.
- Rob Prior's excellent collection,
- Forgotten Futures is a PD RPG by Marcus L. Rowland on similar themes.
by 
created by
- Andy Brick
- Kevin Clark
- The Field Marshal's Starcruiser page
- Earthspace, 2300AD
- ArtCraftGameWorks, Inc. maintain both the Grand Game II (playing the 2300 future history forward) and the Great Power 2109 universe (set in 2300's "past" history).
- Keith Watt's 2063 AD variant rules.