Air – The air domain allows clerics to move swiftly and with ease, and you can gain electrical damage when casting spells
Domain Abilities and spells:
Uncanny dodge – You are able to avoid enemies (Dexterity bonus to Armour Class) even when they are invisible or you are caught flat-footed
Spells – Call Lightning at level 3, Chain Lightning at level 6
Animal
This domain tunes the cleric to his natural surroundings and, much like a Ranger or Druid, he is able to call upon a faithful animal servant to aid in combat.
Domain Abilities and Spells:
Animal Companion – Summon an ally, similar to a wizard’s familiar or a ranger’s animal companion
Spells: Cat's grace at level 2, True seeing at level 4
Death
As the name implies, you are able to summon an shadow ally, much like a phantasm, and gain necromancy related spells.
Domain Abilities and Spells:
Negative Plane Avatar – Summon a phantasmal ally (once a day), who gains in level the same as you
Spells: Phantasmal killer at level 4, Power word kill at level 9
Destruction
Gain spells similar to the arcane school of necromancy, they can destroy their enemies or weaken them with their faith and will.
Domain Abilities and Spells: Smite Infidel: Banish a creature of an opposing alignment, once a day.
Spells: Rage at level 3, Acid fog at level 6.
Earth
This domain allows you to increase your resistance to physical attacks.
Domain Abilities and Spells: Toughness: Gain an additional hit point per level.
Spell: stoneskin at level 4, energy immunity at level 5.
Evil
Manipulate negative energies and gain control of the supernatural evil creature who infest the realms.
Domain Abilities and Spells: Turn Outsider: Similar to turn undead but used against demons such as Balors or other similar creatures.
Spells: Evard's black tentacles at level 4, Weird at level 9
There are so many domains to list that this article wouldn’t do them justice. Please visit http://www.thieves-guild.net/index.php?pid=139 for a truly comprehensive guide on Clerical Domains.
That is more or less all you need to play your chosen Cleric.