Amazon niche store, do you?

I found in the internet an article about building amazon niche stores. Any of you do that? Said we can get commission from the sales generated through our niche stores. Roughly it's almost the same with affiliate system. I think this is a good idea since it's free, however I need some further guide on how to start it. Most articles mentioning about registering at amazon and offering the program or software to build the niche store. If any of you can share how to do that and if you have your own niche store or know it, please give the link as I want to see the appearance of an amazon niche store.