The concept is simple: have as many damage skills at your disposal for solo runs. Specifically, the ones barbs typically build around involving Permawrath. This means you will be running WW, Rend, AND HotA. Seems exceptionally impractical at first, but with the right setup and breakpoints it can be accomplished. HotA and Rend elites until you get 5NV. Rend and WW for the trash. Simple enough, but this is an exceptionally fury dependent build. You would greatly benefit from some reduced costs via itemization
Link to my current barb to see the build:http://us.battle.net/d3/en/profile/oOSlushyOo-1208/hero/36080282
I am still experimenting with passives to see what works best, but using Weapon Master, Brawler, AND Berserker Rage seems to work exceptionally well in white mobs AND elites.