If your CRM Online Organization hasn't transitioned to MSCRM 2015 yet, it will sometime in the next 3 months. There are some exciting new features in Business Rules, my favorite is the addition of the "Else" to the If-Then condition.
I often use Business Rules to Show or Hide fields depending on the value
of another field, for example, If x=y, show field a, otherwise hide field a. Prior to MSCRM 2015, I needed two Business Rules to
accomplish this- One with the logic "If x=y, Show field a" another with the logic "If x not equal y, Hide field a".
Thanks to the addition of the Else condition, I can now accomplish this with one Business Rule:
Note that The ELSE can also include a condition (ELSE IF).