Google Analytics Calculated Metrics
Just started playing with GA Calculated Metrics and... wow. They're such a great complement to other engagement metrics. For Deliberate Digital, I track various engagement metrics and conversions.
Calculated Metrics add fuel to this fire. Looking at a very basic calculated metric of conversions/user, it immediately becomes clear with (page)+(traffic source) combinations are the most valuable.
BTW, turns out Twitter is better source of referrals for me than Google+. What's up with that folks?! :D
The help docs are a decent start, but you really need to read +Avinash Kaushik