You can add a different secondary vehicle, like the Mako or the Hammerhead. You can customize the interior of the Normandy to a great extent, mainly the cargo deck. You have to import a save game from ME2 to reap all it's benefits, and it's just worth it giving it an entire play through just to experience everything the mod has to offer. It makes the game so much more than what it already is, and makes your experience much more satisfying that what you had during your first playthrough. I'm still in the 1st third of the game, 2 missions before the Genophage Cure, and EGM's already awesome. I've installed the Expanded Galaxy Mod for ME3 in my current playthrough.
