Although I find most of the interface to be relatively simple, there are a few changes I would like to suggest.
Alter the Outfitter/Shipyard interface to have a feel similar to that of the Inventory tab. As they stand now, the Outfitter and Shipyard are a bit cluttered with every ship (or weapon) and its variants in one menu. Personally, I think that the outfitter should be divided down into categories such as:
Energy Weapons, Projectile Weapons, Rockets, Homing Missiles, and Other. And then these to be further broken down, such as with Energy Weapons, there is the tab for Plasma Cannons, Ion Cannons, Neutron Blasters, etc. When those menus are accessed, then the variants show up, MkI, MkII, etc. The large and small add-on tabs are still there.
Ships are a bit more picky, as one can deck a Centaur out for transport and mining, or as a weapons platform. Perhaps not have all the variants on there, but rather, just the original name as the tab, and then variants appear when accessed? The other ways I could see dealing with it would be to make tabs for Fighters, Assault Ships, Freighters, etc, but then comes the idea of swing ships.

Yep, Raven, I agree. How about making up a picture to show us what you mean?

Got pic, where does it go?
As far as the pic is concerned, upon selecting the ship, the variants will drop down under it. When clicked off, the variants will go away, and the new ship's variants will show up.

Have we been playing EVE?

Not saying there's anything wrong with that. Like the EVE market interface.

This looks rather like OS X, with the white background and grey arrows, and especially with that font.

Specialized icons for quicker recognition of where you currently are would be nice, but that's a detail.

toshiro: I think Mynt made a few fake folders on his computer to illustrate the point. >_>