Annihilation
Single player modification which features 8 armor classes, 4 vehicles, 29 weapons, 7 spells, 18 packs, 11 turrets, 22 deployables, and 3 moving dropships.
BigBunny's Scripting Site
Home of BBFavourites and many other scripts made by BigBunny
Crunchy's Scripting Site
Home of ObjectiveHUD and many other cool scripts
Mappers Mod
A mod that makes it easier to add new prefab objects into the map editor of tribes
Mental Trousers Tribes scripting stuff
Homepage of PrestoPakPlus, and a good starters guide to scripting
NeoTribes - New Missions for Starsiege Tribes
NeoTribes is a source of quality missions (maps) for Starsiege Tribes.
Poop's Scripts
A collection of scripts coded by Poop. Including SuperFavs.
Presto's PrestoPack homepage
get PrestoPack, a great addon for tribes for clients and scripters
Renegades Mod
A popular mod for Tribes that adds new weapons and makes gameplay faster.
Scripters Underground
Home of BooHUD, KillCountHud, and many smaller scripts
Tribes Voice Pack Downloads
Self-installing voice packs following such themes as Star Trek and Mr. T.