FrogsThemes is something myself and The Floating Frog created over 5 years ago. We tested the water with our flagship themes FolioGrid, which at the time was the first of its kind in as a grid based portfolio WordPress theme.
After tens of thousands of initial downloads of the free version, we then set about creating a Pro version with added extras that we could sell. From there we built the company up and had 18 themes for sale.
It’s now in the capable hands of another pair of experts in the field, but we’re very proud of where we took the site too, so it gets a worthy mention here.
It has membership and ecommerce built into it, works of WordPress Multisite and has tens of thousands of customers to its name. Zendesk is integrated to handle the support and wiki areas and there is also an affiliate system integrated that uses HasOffers.