There are lots of delicious dairy-free foods in the world, lots of yummy low-fat, or gluten-free, or paleo-friendly (or whatever) foods. In general, recipes that fit dietary restrictions and taste good started life as just great recipes that happened to be gluten-free, or low-fat, or paleo-friendly, or dairy-free. A recipe that had to be adapted to meet some dietary need rarely makes it through the translation with its soul intact. (Take it from someone who made the world’s worst vegan frosting.) If you want to feed people gluten-free food, there are whole cultures whose recipes revolve around rice. I’d start there. I’d bet my microplane that your vegetarian friends do not want to eat tofurky, but they’d love a main dish that just happened to be meatless.
A special caveat about recipes that come from people who’ve been on a particular diet for a long time: they forget what their missing foods taste like. So be wary of doughnuts that claim to “taste just like fried” or muffins that “you won’t even know are gluten-free!”