Welcome Arakiel!
Mods such as AIC or Proportions use images from Neoshipset mods. Devnull may be using a few as well, as the Highliner mod.
The links to all these mods can be found in the mod listing over at Malfadator Machinations site, on
Spaceempires.net or on the official sites of the mods' creators (when it applies).
Edit: I mentioned Pirates & Nomads, but if memory serves, the only non-standard image it adds is the Battlemoon.