Here is a company I have been really impressed with. Paizo Publishing.
They have a interesting history, growing out of Wizards of the Coast after Hasbro brought the company. Here's a wiki article about the history of Paizo Publishing.
So what's so cool about Paizo?
The CEO (Lisa Stevens) left WoTC and formed Paizo.
She aquired the licenses for Wizard's magazine Dragon and Dungeon.
Paizo was not just satisfied with licensing mags though. They immediately grew the business by expanding on the storyline adventure idea that had been done successfully in Dungeon magazine.
They launched the Pathfinder series of adventures. Just a word about Pathfinder. They didn't use staid old storylines. The adventures are just damn cool and the artwork is fantastic! (see pic above). If you don't believe selling fantasy adventures and books is not linked to artwork, just ask Larry Elmore. I have spent many a coin over the years just to possess Larry Elmore artwork.
So, after Paizo launched Pathfinder they made sure the brand was superlative in all ways. Not surprisingly, with this attention to being delightful, they grew and grew.
Now, their website collects a huge assortment of awesomeness. Not just their own items, but items from assorted publishers. It is a really good online retail site for all thinks "geeky". For me personally, I can't even go there without browsing their fiction line (and I bought three new Arthurian books while composing this entry).
To me, Paizo is a great example of staying with your passion, expanding within your core interests, building a tribe around your property (Pathfinder), growing by permission-based-marketing, and never failing to delight your readers/customers/community.