OP updated with unique unit/building info:
America
Unique Units: Minuteman - Appears to have a combat bonus when fighting in friendly territory, in addition to the American unique ability of increased sight range; B-17 - Units have a civilian-style triangular unit icon (allowing a fighter unit to stack with it).
Arabia
Unique Unit: Camel Archer - Can move after combat. Weak to Pikemen.
Unique Building: Bazaar - Provides an additional instance of each improved luxury resource near the City.
Aztec
Unique Unit: Jaguar - One preview suggests that the Jaguar has a bonus fighting in Jungle, and can heal itself by defeating an enemy unit (similar to the Janissary).
Unique Building: Floating Gardens - +2 Food per worked lake tile, regular Water Mill food bonus +15%
China
Unique Unit: Chu-Ko-Nu - May fire twice per turn.
Unique Building: Paper Maker - +4 Gold, +1 Science for every 2 Citizens, 1 Science specialist slot.
Egypt
Unique Units: War Chariot - Ffaster than the normal chariot, doesn't require Horse resources.
Unique Building: Burial Tomb - +2 Culture, no maintenance +2 happiness; double Gold in plunder if captured.
England
Unique Units: Longbowman - range of 3 instead of 2; Ship of the Line - faster and stronger than normal Frigate unit.
France
Unique Units: Musketeer - Stronger than normal Musketman unit; Foreign Legion - Combat bonus outside friendly territory.
Germany
Unique Units: Landsknecht - One report suggests that the Landsknecht has the same stats as the Pikeman, but is cheaper to produce; Panzer - Can attack again after combat, gets a combat penalty when attacking Cities, has limited range of sight.
Greece
Unique Units: Hoplite - Stronger than normal Spearman unit; Companion Cavalry - Stronger than normal Horseman unit, allegedly also gives increased Great General points.
India
Unique Unit: War Elephant - Much stronger than normal Chariot Archer unit, but one movement point slower
Unique Building: Mughal Fort - 4 maintenance, +2 Culture, provides Gold after Flight is researched.
Iroquois
Unique Units: Mohawk Warrior - +50% combat bonus in Forest or Jungle.
Unique Building: Longhouse - Requires Metal Casting, +1 Production from each worked Forest tile, 1 Engineering specialist slot.
Japan
Unique Units: Samurai - Automatically receives Shock I promotion (bonus fighting in open terrain), success in combat with a Samurai has an increased chance of generating Great Generals; Zero - Combat bonus against other Fighters, can perform missions within its range of 8: attack enemy aircraft and ground units, scout enemy positions, defend against enemy air attacks.
Ottomans
Unique Units: Sipahi - +1 Sight range, bonus against Mounted units, penalty on defense, can pillage enemy tile improvements at no additional movement cost; Janissary - Receives a combat bonus on the attack, automatically heals all damage when it defeats a non-Barbarian unit.
Persia
Unique Unit: Immortal - Heals at double rate.
Unique Building: Satrap's Court - +25% gold, +2 happiness.
Rome
Unique Units: Legion - Can build Roads and Forts like a Worker; Ballista - Stronger than normal Catapult unit.
Russia
Unique Unit: Cossack - Does more damage to wounded enemy units.
Unique Building: Krepost - +15 XP to all land units, -50% Culture cost for buying City tiles.
Siam
Unique Unit: Naresuan's Elephant - Combat bonus vs other Mounted units, can move after attacking.
Unique Building: Wat - +3 Culture, +50% Science, 2 x Scientist Specialists.
Special Ability: Father Governs Children - Food and Culture from friendly City-States increased by 50%.
Songhai
Unique Unit: Mandekalu Cavalry - +30% bonus vs. Cities.
Unique Building: Mud Pyramid Mosque - ???
Sinatar said:
You just get an extra map or two, which considering the fact that the game uses a random map generator makes them pretty worthless.
You also get the Babylonia civilization.