I was playing around with a variety of things this morning and discovered a trick using the {EnhanceLevel} tag. I created an Improvement called Orbital Defense Factories.
{Improvement}
{S_Name}Orbital Defense Factories{/S_Name}
{S_InternalName}OrbitalDefenseFactories{/S_InternalName}
{S_Type}SuperProject{/S_Type}
{S_TechRequirement}Industrial Complex{/S_TechRequirement}
{Cost}800{/Cost}
{AI}15{/AI}
{S_Description}Creates a series of satelites that upgrade our Defenses by 5%{/S_Description}
{S_BriefDescription}Minorly increases defenses.{/S_BriefDescription}
{!-- Mod to Defenses --}
{AbilityType}2{/AbilityType}
{AbilityAmount}5{/AbilityAmount}
{S_IconName}Orbital_Terraforming_Unit.png{/S_IconName}
{S_QueryGraphicName}Orbital_Terraforming_Unit.png{/S_QueryGraphicName}
{EnhanceLevel}1{/EnhanceLevel}
{/Improvement}
So what, you ask. In addition to adding a small bit to your Race Defense abilitiy (in this case, 5%), the cool factor is: it DOES NOT take up any of your usable tiles!
In this fashion (I think, though I haven't tried it yet), you could create Trade Goods that don't take up any tiles either. Your Yellow, Orange and Red tiles become very valueable indeed. Also, when you build the Improvement on the tile, once its built, the tile turns Green!