My ideas are:
Sumer
Starting: Knowlege of alphabet and a Libary
Ancient: Cost of all buildings reduced by 1/8
Medival: Knowledge of University
Industrial: Recieve a free wonder in one of their cities
Modern: Free guerilla promotion to tanks
Incans
Begin the game close to an acient relic
Ancient: +2 food from mountain
Medivel: Double defence bonus on hills
Industrial: +5% intrest on gold reserves
Modern:
Mayans:
+25% science
Ancient:
Medieval: half-cost temples
?
?
Mali
Start out with +3 trade from deserts
Ancient: +1 archer defence
Medieval: +%100 caravan gold
Inudustrial: +50% gold
Modern: Half unit rush
Vikings: Berserk(replaces legion)
Starting: Galleys can travel on ocean squares
Ancient: +1 berserk attakc
Medival: No penalty for amphibiouse assults
Industrial: Naval support doubled
Modern: Recieve the knowledge of Electricity
Carthage: Trimene replaces galley, Numidian calvalry replaces horeseman
Begin teh game with cheaper promotions (2 experience per promotion instead of three)
Ancient: Half goldrush (Ikael's idea)
Medieval: +1 naval attack
Industrial: +1 desert production and trade
Modern: Captured cities gain +1 population (may not be accurate, but it would be a cool power in the game)
Celts:
New cities start with a free offensive untit* (depending on available techs, ei if chivalry is known it starts with a night, if combusten is known a tank)
Ancient: When retreating, the defending unit gets +1 experience instead of a full-on promotion
Medieval: Free Great Builder
Industrial: Recieve a Catheradal
Modern: +1 production on hills
Babylon:
Start: Begin the game with all governments available
Ancient: +2 production from deserts
Medieval: No anarchy
Industrial: For Fudalism and Communism, temples/catheradals and libaries/universites effect is halfed instead of eliminated
Modern: +1 Tank attack
Korea
Start: Capital begins with +1 population
Anicent: Libaries produce a small amount of culture
Medieval: No anarchy
Industrial: Knowledge of University and a University in the capital
Modern: +1 trade from sea squares
Goths
Start: Alliance with barbarians**
Ancient: New warriors and legions are vetrans
Medieval: +1 strenght to offensive units*
Industrial: Captured cities generate +%50 gold
Modern: Calvalry are upgraded for free
Portugual: Caraval replaces Galleon, Frigate replaces Galleon, explorer replaces milita
Start: Tripple Exploration cash
Ancient: +1 explorer movement
Medieval: +2 strenght to Frigates, +2 movement to caraval
Industrial: New cities start with +1 population
Modern: +1 food to plains
Dutch: Merchantman replaces Galleon
Starting bonus: Knowledge of currency
Ancient: Markets produce culture
Medieval: +2 merchantman defence
Industrial: +1 hammer from sea
Modern: +1 gold per specalist (in city square)
Ottomans: Janissary replaces rifleman
Starting: Free horseback riding tech
Ancient: +1 food from plains
medieval: Cheaper walls
industrial: +2 Janissary attack
modern: Cheaper Catheradals
Khmer: Ballista Elephant replaces Horesman, Ballista Horesman replaces Horesman
Starting: Knoledge of Construction
Ancient: -1 Ballista Elephant speed, +2 attack
Medieval: Learn where the location of a relic is
Industrail: +1 food to woods
Modern: Catheradals, Universities, and Banks can be built without a prerequisit building
Ethiopia
Ancient: Recieve a free technology at the beginning of every era (that you can choose)
Starting: Begin the game five turns earilier than everyone else
Medieval: +1 culture to working desrt squares
Industrial: Temple cost reduced by %50
Modern: +1 production to working city square
Iroquois: Mounted warrior replaces horeseman, dog warrior replaces legion
Starting: Half-cost mounted warriors
Ancient: +1 food from sea squares
Medieval: Settlers automatically retreat to one space away when attacked
Industrial: +2 food from forest
Modern: +1 production from grassland
Souix: Mounted warrior replaces horesma, dog warrior replaces legion
Starting: Knowledge of horesback riding
Ancient: +1 dog warrior attack
Medieval: Acsess to all resources
Industrail: Half-cost courthouse
Modern: +1 food from plains
Persia:
Starting: Free settler comes from capital when it reachse three pop.
Ancient: Wonders cost 33% reduced in capital
Medieval: Automatically recieves a free technology that an opponent civ. has when capturing one of there cities
Industrial: Fudalism does not close libaries and universities
Modern: ?
Byzantines: Cataphract replaces knight
Starting: City squares has 1/2 movement cost instead of 1
Ancient: Wonder cost reduced by %25
Medival: +1 attack to cataphract
Industrial: Recieve a great person
Modern: New cities start out with a temple and a libary
Hittie
Starting: New cities start with a temple
Ancient: Economic thresholds are %20 lower (except for World Bank)
Medival: +1 calvalry movement
Industrail: +1 population in capital
Modern: +%25 gold production
Holey Roman Empire: Landchester replaces pikeman
Starting: New cities start with an amount of gold (determined on dificulty, less for capital, incresed as year and number of cities increase)
Ancient: Recieve contact with all civilizations
Medieval: Knowledge of Fuedalism
Industrail: Courtouse cost reduced by half
Modern: Spies can only reduce %25 fortification instead of %50
I might continue this list later on.
*Offensive units: Warrior-Legion-Knight-Tank
Seige units: Catapult-Cannon-Artillary
Defensive units: Archer-Pikeman-Riflemen-Infantry
Calvalry: Horesman-Knight
Naval and arial are self-explanatory
**Barbarians are friendly and you cannot attack them with an alliance. When a gothic unit goes onto a barbarian city for the first time gifts or experience will be awarded to make up for the bonuses in conqering them. When the Goths are at war, barabarians will randomly spawn and attakc the civilization they are at war with.