a) Referrals:
Referrals are users that you have "referred" using any of your tribe's available growth tools (such as invite codes, referral URL, widget, etc.) These users can earn you money (a 50% rev-share) when they upgrade their own, or someone else's account (via gifting) to Snapzu Platinum status.
b) "Support this Blog" button:
All users, even those you didn't refer, can support your blog with the optional support button that's available on the widget. When supporting your blog, users get Platinum membership in return.