Here are some planetary bonuses I thought of off the top of my head. Hopefully they could be usefull. I tried to find sources for their inspiration where I could. I'll have some more over the next few days.
List of Planetary Bonuses:
-Resonance Fractures (Ice Planets & Asteroids): +20% crystal, +10% Trade , -10 Population (Crystal is easier to mine and sell, unstable crystals in the planet's crust reduce the places people can live).
-Deep Gravity Well: Gravity Well Radius +40%
-Porous Core: Gravity Well Radius -20%, -10% crystal, -10% metal
-Organic Artifacts: +25% Culture Rate (based on Season 1 Episode 4)
-G'Quan-Eth Plants: +25% Culture, +25% Trade, +0.5/sec Tax (Season 1, Episode 12)
-Dock Worker Union: +10% Hull Restore Rate, +10% Trade, -0.5/sec Tax (Season 1, Episode 12)
-Centauri Relics: +10% Trade, +0.5/sec Tax (Season 1, Episode 13)
-Defense Network: Tactical Slots +5, +10% Weapons Range
-Temporal Fluctuations: -10% Trade, -10% Weapons Range (Season 1, Episode 20)
-Morden's Promises: +10% Weapons [For Friendlies], -5% Weapons [Enemies] (Season 1, Episode 22)
-Drazi Dispute: -10 Population, -20% Growth Rate
-Rogue Telepaths: -0.5/sec Tax (Season 2, Episode 8)
-Earth Force Marines: +25% Resistance to Bombardment (Season 2, Episode 10)
-Ranger Enclave: +10% Resistance to Bombardment, +10% Culture (Season 2, Episode 9)
-ISN News Hub: +25% Culture, +10% Growth Rate (Season 2, Episode 15)
-Markab Plague: -20 Population, -20% Growth, -1.0/sec Tax (Season 2, 18)
-Alien Inquisitor: -0.5/sec Tax, -5% Trade (Season 2, Episode 21)
-Trade Hub: +25% Trade, +0.5/sec Tax
-Dust Dealer: -0.5/sec Tac, +10% Growth Rate (Season 3, Episode 6)
-Parasitic Aliens: -10 Population (Season 3, Episode 7)
-Nightwatch: -15% Culture Spread Rate, +15% Population Growth Rate (Season 3, Episode 8)
-Martial Law: -10% Population Growth Rate, +5% Trade (Season 3, Episode 9)
-PSI Cop Outpost: -10 Population, +5 Tactical Slots (Season 5, Episode 6)
-Telepath Colony: +10 Population, +15% Growth Rate
-Brakiri Festivals: +10% Growth Rate, +0.5/sec Tax, +20% Culture Spread Rate (Season 5, Episode 8)
-Pirate Raiders: -15% Trade, +10% Weapon's Firing Rate (Season 5, Episode 15)
-Cult of Personality: +20% Growth Rate, +10 Population, +0.5/sec Tax (Season 5, Episode 19)
-Civilian Defenses: +10 Resistance to Planet Bombing, +5/sec Hull Repair Rate
-Targeting Network: +5% Weapons Fire Rate
-Orbital Infrastructure: Structure Build Rate +33%
-Orbital Docks: Hull Repair Rate +5/sec
-Entertainment Hub: Culture Spread Rate +15%, Tax +1.0/sec (Based on Entertainment Hub from game)
-Orbital Commerce: +10% Trade, +5 Logistics Slots
-Cavern Systems: Max Population +20, Planet Health +750 (Based on Habitable Cavern System)
-Terraformed: Trade income +10%, Planetary Population +500 (Based on Expert Agrarian Society)
-Fertile World: Trade income +15%, +0.5/sec Tax
-Minbari Miners: +40% Crystal Extraction Rate (Based on Expert Crystal Miners)
-EA Miners: +40% Metal Extraction Rate (Based on Expert Metal Miners)
-Ionic Storms (Volcano & Desert Only): Max Population -20, -10% to Weapons Range (Based on Ionic Storms from Sins)
-Minbari Artifacts: +20% Trade Income (Based on Kalanite Deposits)
-Massive Glaciers (Ice & Terran Only): Trade Income +10% (Based on Massive Pure Glaciers from the game)
-Mega Fauna (Non Asteroids Only): Max Population -15, Trade Income +15% (Based on Mega Fauna from the game)
-Natural Thermal Lifts (Desert Only): Structure Build Rate +20%, +15% Growth Rate (Based on Natural Thermal Lifts from game)
-Penal Colony: Structure Build Cost -50% Build Cost, Buildings take 50% longer to build. (Based on Penal Colony form the game)
-Pirate Outpost: -10% Trade, +1.0/sec Tax (Based on Plundered Booty from game)
-Pirate Hub (Pirate Base Only): +2.5/sec Tax (Based on Plundered Booty from game)
-Shallow Gravity Well: -33% Gravity Well Radius (Based on Porous core from the game)
-Industrial Outpost: Extra Constructors +2 (Based on Raiders Outpost)
-Frontier Outpost: +10% Metal Extraction Rate, Extra Constructor +1 (Based on Raiders Outpost)
-Drug Trade: Cultural Spread Rate +10%, Trade income +10% (Based on Spice Trade from game)
-Spice Trade: Cultural Spread Rate +5%, +1.0/sec Tax (Based on Spice Trade from game)
-Tundra Farms (Ice Only): Max Population +25, +5% Growth Rate (Based on Tundra Farms from the game)
-Toxic Waste (Dessert / Volcanic Only): -15 Population, +0.5/sec Tax
-Weapons Test Facility: Max Population -20, Tactical Slots +5 (Based on Weapons Test Facility from the game)
-Cultural Center: +20% Cultural Spread Rate
-Resistance Fighters: -5% Weapons Fire Rate, -5% Hull Repair Rate, -10 Max Population
-Unstable Mantle (Non Asteroids): -15 Population, -1000 Planet Health
-Strong Magnetics: Anti-Matter Recharge Rate +15%
-Debris Field: Weapon's Ranges -15%
-Incorporeal Fauna: -10 Max Population, +10% Trade
Artifacts:
The Great Machine: +25% to Research?
-Weapon's Schematics: +10% Weapons Fire Rate, +5 Weapons Damage (Season 3, Episode 1)
-Terrorist Attacks: -20% Trade, -0.5/sec Tax, -10% Growth Rate
-Shadow Weapons: -25% Culture Spread Rate, +10% Weapon Damage, +5% Firing Rate (Season 3, Episode 14)
-Lorien: +25% Resistance to Bombing Damage on all planets? (Season 4, Episode 2)
-Frozen Telepaths: +25% Research? (Season 4, Episode 17)
Thoughts? Use and tweak and change them as you wish. 