You can make the search more easier by pressing on the ''downloads'' button on tthe top corner
You'll see the most downloaded mods I think that the massive add on is one of them

Gah! I know, I found it about a 1/2 hour after making this thread, sorry for the n00bish thread...

what does it do?

Its truly excellent, Star Trek ships, X-Wings, TIE Fighters, Babylon 5 ships, extra story missions, a complete model of our solar system, new weapons, basically way too much stuff to list here because its a load of seperate mods joined together into one big one, but it doesn't affect the way you play the main storyline at all, it just enhances it, best mod Ive ever seen for any game (except Counter-Strike maybe, but thats a game in its own right)