A few days ago, there was a topic talking about possible D2-style runes. There was a lot of good discussion there, and I had a couple of ideas on how it should probably go. This is me taking these thoughts and running with them.
So, the basic idea is that the current gems are too limited and too easy to game. There is no variety in slot choices: Weapons are always Emeralds (other than people desperate for LOH), helmets are always Amethysts (other than MF sets), and everything else is just your primary stat with MAYBE a couple of Amethysts if you are short on health.
Caveats to this are the cautionary tales from D2. The runes were cool, runewords are the devil. Crossing class abilities is generally not smart, and they should not ever be so powerful that they end up replacing your gear or totally warping what you're looking for.
So here are the basics:
1) Any gear slot other than Follower Special that cannot currently roll sockets gains the ability to roll one slot. This important to how the system ends up working, read on.
2) The Power Stones end up emulating almost every single affix in the game that is not already present on gems (and some which are but are slot-limited)... but at low power. You will never see a +70 Resist-All Stone, but you may just get 5.
3) Power Stone affixes are limited for the most part to the same categories of items which can hold that affix. Class-specific ones are the exception here: they can go onto any slot the class-specific items which hold them normally occupy (so, for example, you could put APoC on a 2H Axe)
4) The baseline of power for the best Power Stones is roughly what you can roll on an iLvl 30 item. Adjustments are made up and down from this line for fairness and usability (and for presence, since somethings like Indestructable are never there until a bit higher)
5) It needs to be said, the presence of an affix will NEVER give a class-specific benefit, resource, or ability to a different class.
For all of this, creation is handled by the Mystic, the craftswoman met in the Spider's Lair but removed during Beta. There is no need for new materials (though Pages and Tomes of Mysticism would likely be added). Base Gems and Salvage work, along with probably a few of the very basic Power Stones which would start dropping.
*whew*, now for the part that took freaking forever and really isn't done, the specifics. Remember that these currently only represent what would be the maximum available with a capped-out crafter. Lesser amounts will be craftable as the Mystic comes up the ranks. I will be editing this post frequently as I figure more out and according to feedback both here and elsewhere. I'll try to sort by category, and in some cases (like Class Skill boosts) I'm going to skip several for now.
Note that "Armor" means Chest, Helm, Legs, Bracers, Shoulder, and Boots. "Jewelry" means Amulet and Ring. "Offhand" means Mojo, Source, or Quiver.
Maximum Fury: +9 Max, usable on Weapons and Belts
Hatred Regen: 0.75 hatred/second, usable on Weapons, Chest Armor, and Offhand
Maximum Discipline: +5 Max, usable on Weapon, Offhand, and Chest Armor
Spirit Regen: 1.5 Spirit per Second, usable on Weapons and Helmets
Life per Spirit Spent: 1.5 Life per Spirit Spent, usable on Weapons and Helmets
Mana Regen: 5 MpS, usable on Weapons, Offhands, and Helmets
Max Mana: +50 Max, usable on Weapons, Offhands, and Helmets
Arcane Power on Crit: 5 APoC, usable on Weapons, Offhands, and Helmets
Max Arcane Power: +8 Max, usable on Weapon, Helmet, and Offhand.
<Gigantic list, will edit in later>
Specific Resist: +25, usable on Amulet, Armor, Ring, Shield, and Offhand
Resist All: +10, usable on Amulet, Armor, Ring, Shield, and Offhand
Damage Reduction: 3% reduction versus Elite, Melee, or Ranged, usable on Armor or Shield
Armor: +90, usable on any other than Weapons
Blind: 2% on hit, usable on Weapons and Jewelry
Chill: 2% on hit, usable on Weapons, Shoulders, and Jewelry
Fear: 2% on hit, usable on Weapons, Helmet, and Jewelry
Freeze: 2% on hit, usable on Weapons, Belt, and Jewelry
Immobilize: 2% on hit, usable on Weapons, Boots, and Jewelry
Knockback: 2% on hit, usable on Weapons, Bracers, and Jewelry
Slow: 2% on hit, usable on Weapons, Pants, and Jewelry
Stun: 2% on hit, usable on Weapons, Gloves, and Jewelry
Experience: +15 per kill, usable on Jewelry, Weapons, Armor, Offhand, and Shield
Health Globe Bonus: +500 healed per globe, usable on Jewelry, Armor, Offhand, and Shields
Life On Hit: +25 LOH, usable on any slot.
Life On Kill: +100 LOK, usable on any slot
Life Steal: 2%, usable on Weapons
Life Regen: +20 Life per Second, usable on Armor and Jewelry
Indestructable: ...what it says. Usable on any slot
Move Speed: +10%, usable on Boots
Thorns: 30 damage to melee attackers, usable on Amulet, Armor, and Shield
Thanks for making it this far, and PLEASE share your thoughts, reccommendations, and any constructive criticisms you may have.