Tribes Universe offers free download of:
As an appetizer for Tribes Ascend.
Starsiege: Tribes
Tribes at wikia.
Starsiege Tribes Master Server Home page
Plasmatic's Code Forge
TribesNext is a community initiative to restore online functionality to TRIBES 2, Dynamix's final entry to the Tribes series. The patch allows players to create new accounts, host and join online servers, and have a generally kick-ass time. TribesNext is completely free.
TribalOutpost.com Everything Tribes. Maps. Scripts. Styles. More.
SHIFTERmod
IronsphereRPG (discontinued)