If one had to pick a single hot topic on every community professionals mind right now, it would be ROI. Requests from leadership teams - often an analytical and data driven bunch - push community practitioners to nail down hard numbers for work that is notoriously holistic and qualitative. This makes Community ROI seem daunting and unattainable to many in this space - but fear not. There are many brilliant minds hard at work to solve this challenge, and even more resources available to represent their efforts.

This Harvard Business Review article from Rachel Happe focuses on walking through the model for quantifying hard financial value for online communities.
...While this eBook from the minds at The Community Roundtable details the step-by-step process for calculating ROI. Need a calculator to jump start your math? They have you covered here.
How to Calculate the ROI of Online Communities from Rich Millington is a comprehensive, detailed and widely accessible manual on making ROI a reality for your work. While this one is a long read, it is a goldmine.
These Best Practices For Measuring the ROI of Online Communities from Oracle break out approaches for Customer Support, Innovation, Loyalty, Awareness and Commerce use cases.
If you a looking for a gut check on your calculations, or perhaps hoping for a jumping off point, this ROI Calculator from Vanilla Forums can help you get a pulse on the value of your customer community.