Hi Dragontree and welcome to the waymarking forurms. Your list is quite impressive and those that have posted about other Points of Interest websites are on the right track - much of the list would not fall under waymarking. Those POI websites are better served for the phone book/yellow pages of listings. Some of your ideas may already be incorporated into existing categories. You may want to take a look at Self Serve Pet Wash, Quilting Shops, Self Serve Car Wash, for some of the ideas you've already mentioned. I know the Independent Artist Supply Store category includes photography equipment. And the Racetracks category also includes go-karts.
I think there was once talk about Independent Toy Shops, Scrapbooking stores, Recording Studios, Magician Shops, Kennels....so some of those might be feasible down the line.
Maybe narrow down the list to what you are passionate about and see if others have similar interest in a topic that is educational/interesting/worth visiting.
Good Luck!