I have been staring at an open word document for the past half-hour or so, and cannot think of a single thing to do with these Gifts. I think I am thinking about it too hard, so instead I am just going to wing it here, and write down ideas as they come up. If you think something is too strong/too weak, feel free to help out on it. Maybe recommend a level requirement, or a way to make it worth the Gift Slot. Progression will be the same as Warlock, so if you wouldn't take it as a Warlock, it will be the same cost on this.
Greater Command
Prerequisite; Knowledge Domain, Command
If the target of your command spell fails its saving throw, you can also utter a second command that it must follow as its reaction immediately.
Aura of Life
Prerequisite; Life Domain, 5th level
Allies within 5 feet of you regenerate health equal to half of your Wisdom modifier, as long as you are conscious.
Burning Brilliance
Prerequisite; Light Domain, 5th level
Your light spells deal damage to creatures now. A creature within 5 feet of a source of light created by you, or within an area of effect such as Faerie Fire, takes 1d8 damage for each level of the spell slot spent. In addition, your Light Cantrip (Which does not deal damage), gives disadvantage to a creatures attacks and Dexterity saves, until the start of your next turn, when you cast it within 30 feet of them. A creature affected by Light in this way cannot be affected again for 10 minutes.
Gift of Yggdrasil
Prerequisite; Nature Domain
You can cast Barkskin without using a spell slot.
Eye of the Hurricane
Prerequisite; Tempest Domain
When you cast Fogcloud, you are able to choose a number of creatures equal to your wisdom modifier, within 30 feet of you, to be immune to its effect, allowing them to see clearly.
Charming demeanor
Prerequisite; Trickery Domain
When you use the Charm person spell, as long as you did not have the target do anything specifically bad for it (Loan you a small amount of gold, go for a walk instead of standing guard, etc.) It will not know that it was charmed.
Trained in War
Prerequisite; War Domain
You may choose a fighting style from the list available to the Paladin
Sword of the Gods
You can choose a single Sacred Weapon Form, representative of your god. As an action, you can summon this weapon to use in battle. It counts as magical for the purposes of overcoming Resistance and immunity to non-magical attacks. It also counts as a holy symbol for the purposes of Spell-casting. You can also talk with your DM about having the weapon deal a Damage type that fits your god, such as Thor giving Lightning damage, to add more personal flavor to your cleric.
Divine Force
Prerequisite; Arcana Domain (SCAG)
When you cast Magic missile, you can choose for it to deal Radiant Damage instead of Force.
Arcana Divine
Prerequisite; Arcana Domain, 3rd Level
You can add 1 wizard spell of your choice to your Cleric Spell list, outside of the ones added by this domain. You can change this spell when you gain a Cleric level. This spell can then be included in your prepared spells but, unlike the Domain Spells, does count against your number of Spells prepared. The spell must be of a level for which you have spell slots.
Greater Knowledge of the Ancients
Prerequisite; Knowledge Domain, 5th level
When you choose a skill or tool for your Knowledge of the Ancients Channel Divinity, you gain Expertise in that skill or tool, instead of proficiency.
That is all I have for now, I might get more out soon. If you have your own ideas, feel free to offer them up. I particularly need some for base clerics without prerequisites, keeping in mind how they might interact with these ones.
------------------------------------------------------
New day
New Additions
Flurry of Blades
Prerequisite; Martial Weapon Proficiency, 5th level
When you take the attack action, you can make a second attack.
Through the Eyes of the Gods
Once per long rest you can gain True Sight for 1 minute, out to 20 feet.
Tempered Shield
Prerequisite; Forge Domain (UA)
When you cast shield, you also add your Wisdom Modifier to your AC.
Greater Bane
Prerequisite; Grave Domain (UA)
When an enemy affected by your Bane spell attempts an attack or skill check, the die rolled is 1d6 instead of 1d4.
------------------------------------------------------
Some Warlock ones that work just as well for Cleric. After all, it would be kind of silly if a Nature god couldn't give free Speak with Animals.
Beast Speech
Prerequisite; Nature Domain
You can cast Speak with Animals without expending a spell slot.
Arcane Sight
Prerequisite; Arcana Domain
You can cast detect magic without expending a spell slot.
Mask of Many Faces
Prerequisite; Trickery Domain
You can cast Disguise Self without expending a spell slot.