Battlestar Galatica: TOS, The new Battlestar Galactica, Buck Rogers, And Dr. Who would all make for some interesting mods I might be interested in playing.
How about Bucky O'Hare & The Toad Wars?
A new ship model that has the Jupiter 2 design from the Lost In Space movie would be nice, and to go along with it you could toss in the new Robot & the Original Robot models from that franchise.
What about a Duck Dogers mod?
Daffy in a space suit, Porky in half of one, Marvin the Martion, and a whole slew of the Looney Tunes monstersall vying for control of the galaxy? Cant go to far wrong with that so long as you make it some sort of a "humerous" mod.
Another one I'd love to see would be one that has renders of Spaceman Spiff and his ship (from the greatest comic strip that ever was but is no more "Calvin & Hobbes".)
A Macross, Battletech, Mobile Suit Gundam, or Star Blazers mod could work great with this game if it were in the right programmer's / modder's hands.
There's TONS of both great and not so great stuff out there that COULD be modded for this game that hasn't been yet really. You just have to sift around in asll those dusty old memory banks a bit. Ohhh yeah, and you'd have to convince the right person or group of people that an enormous undertakig like modding a game just to make it look and play a tiny bit cooler would be worth thier time.