Modifications and Add-ons

Fleet Action: A Wing Commander Tribute - http://www.strategyplanet.com/homeworld/fleetaction/
Total Conversion based on the Wing Commander series of games

Homeworld Extreme - http://www.strategyplanet.com/homeworld/hwex/
An ambitious project to tweak the HW .EXE

Homeworld Newbie Forums - http://p210.ezboard.com/bhomeworldnewbieforum
Basic tutorials, question and answer forum, and other useful resources.

Karos Graveyard - http://hw2.tproc.org/wiki/karosgraveyard/
Contains documentation, a scripting reference, and modification tutorials.

Star Trek: Fleet Academy - http://www.strategyplanet.com/homeworld/zeelich/
A popular modification for Homeworld that allows you to play using Star Wars ships.

Star Trek: Homeworld - http://www.strategyplanet.com/homeworld/stvsw/sth/
Actually several mods, based on different Star Trek series

Turanic Raiders Mod - http://www.strategyplanet.com/piratesmod/
Allows playing of the Turanic Raiders in multiplayer, also adds some never before seen ships