Tribes Vengeance has a lot of customized content. Many of those contents, were publicly released and have been put on this website, free for download. Click on the name of the type of customization to go to their respective downloading page. Descriptions will soon be updated and they will be accompanied by pictures, etc.
All sorts of special effects, including projectile trails and more!
Add things to your HUD.
The HUDs of some people who have shared it.
Customized quickchats. Some of which only the text changes, some include new sounds.
Customize your reticle and/or crosshair.
Customize your ingame sound effects.