did you check out the modding section of the fourms...
once you downloaded them you need to install into a specific folder
XP: c:\Documents and Settings\user\Local settings\Application Data\Ironclad Games\Sins of a solar empire\
vist: C:\Users\username\AppData\Roaming\Ironclad Games\Sins of a Solar Empire\
ps:replace user with your username on your computer
usually all of the mods are for the latest version of the game, so you need to update or they just have it for the entrenchment version in which you need to buy to play it
basically there are a mod for all of the space sci-fi such as Babylon 5 Battlestar galactic and the star trek (there is a version for 1.17 and the version for entrenchment is still being developed), there is also the Mad Scientist, and the Distant Star, or the 7 Deadly Sins, those are the just the most popular total mods
of course there are some minor mods such as Graphics, volumetric explosions mods by Mansho0ter and Blinking (ahh) and the movement mods by Mansh00ter, however, almost every mod contain mansh00ter's mods (the graphic and volumetric explosions one)
