I do not have a specific build, but here is some advice and skill selections.
Fury is gained in several ways:
- Successfully attacking
- Using fury-generating skills
- Taking damage
So for max fury gain, you want to attack quickly, focus on fury-generating skills, and take damage. This last point may mean you avoid armor and skills that add damage mitigation, and perhaps focus on life-regeneration instead.
Here are skills that help gain fury:
- Bash + Instigation: 12 fury per attack
- Cleave + Reaping Swing: 5 fury per attack, + 3 per enemy struck
- Frenzy: 3 fury per attack, and up to +75% attack speed for faster attacks
- Whirlwind + Wind Shear: 1 fury per enemy struck
- Ground Stomp + Foot Of The Mountain: 30 fury per use
- Leap: 15 fury per use
- Ancient Spear + Skirmish: 30 fury per use
- Revenge + Vengeance Is Mine: 5 fury per enemy struck
- Furious Charge + Stamina: 15 fury + 8 per enemy struck
- Overpower + Momentum: 12 fury per enemy struck
- Threatening Shout: 15 fury per use
- Battle Rage + Into The Fray: for 30 secs, critical hits gain 15 fury
- War Cry + Charge!: 60 fury, but increases armor so reduces damage taken
Passives that gain fury or help Wrath of the Berserker:
- Animosity: +10% fury gained
- Unforgiving: +1 fury every 2 seconds (I am not sure if this counts for Berserker though)
- Inspiring Presence: Double-duration shouts (see Battle Rage above)
- Superstition: chance to gain 3 fury when hit by raged/elemental abilities
- No Escape: Weapon Throw critical hits gain 14 fury
- Boon of Bul-Kathos: reduce Wrath of the Bersekrer cooldown by 30 Secs
- Weapons Master: Increased attack speed with Polearm/Spear (so can use fury generators faster)
Since many of the above skills deal with either per-attack or per-enemy-struck bonuses, you could specialize multiple builds, for keeping Wrath up when fighting bosses/elites, or fighting large swarms of monsters.
I don't think you can continuously generate 25 fury a second to keep Wrath up for a long time, but I think you could have great success activating it and then unleashish some big/AOE attacks to generate enough fury for 5-10 seconds more fun. And so you take Boon of Bul-Kathos, you might be able to keep Wrath up for 25-30 seconds out of every 90.
If I were to try to create a build out of all this, I think I would go for the critical hit synergy. Wrath and Berserker Rage both give you more crit chance, and Into The Fray turns crits into fury. Overpower can be cast more often if you crit a lot, and it generates fury every time it strikes an enemy (Momentum). Throw in Frenzy and Animosity for constant passive fury generation, add enemies to taste, blend well, and enjoy!