For example, with a following build (a 'standard' WW build with Boon of BK and Insanity as WotB rune)
Barbarian - Game Guide - Diablo III
Once you start fighting with WotB up and start to WW, you will do double damage even after the WotB is over, as long as you keep spinning.
Also be careful that when you enter Berserker during WW, the damage bonus will not be applied! Make sure to activate WotB then WW
I've been incorporating this with Earthquake to provide decent burst dmg for elite fights. Keep in mind the CC effects such as freezing can interrupt your WW.