Couple I haven't seen mentioned. For cajun style po' boys you might want to hit Po' Melvins in Irving, at Beltline and Walnut Hill, just a few blocks south of where 161 hits Beltline. They have a website with an auto-play video, so if you are at home or somewhere you don't mind audio/video go ahead and Google it.
Check out their menu though, lots of Cajun style shrimp, gumbo, jambalaya, and of course po' boys. Their cobler a la mode is fantastic and if you go in the mornings on the weekends they have an all you can eat breakfast that you'll need help prying yourself away from. http://www.pomelvins.com/Po%20Mels%20Jan%202011.pdf You just can't go wrong with a place with a famous house drink they call the "Yo' Mama"
In the fusion arena there's a little place a few miles north, in Coppell on Beltline near where Beltline turns into Denton Tap, a couple miles north of the 635/Beltline intersection. It's called Taco Naan and it's a mix of Mexican and Indian. You can get Barbacoa wrapped in naan, and chicken 65 on a tortilla if you want. I haven't gotten up the courage to try it myself, but some co-workers swear by it.
http://www.yelp.com/biz/taco-naan-coppell
Taking a slight jaunt south-east we come to Walnut Hill and Story Road in Irving. There's a little southern style place here called Southern Recipe. When I say southern style, I mean deep south, Georgia, South Carolina, that kind. It's a "meat and three" place. You order a entree(usually something fried) and they ask you what three sides you want(also usually fried). Want a vegetable for a side? No problem honey! How about green beans(cooked with bacon and ham)? What about some carrots(candied and served with a thick sweet brown sugar glaze)? Surely you can't go wrong with some nice apple slices? Cinnamon and sugar glazed and baked. What about the corn? Cream style, of course, what are you, a yankee? They serve you on big platters, and usually at least one of the sides has to come on a separate plate or bowl because the portions are enormous. And I'm using a Dallas-based scale for that comparison, don't say I didn't warn you.
They also serve breakfast all day. http://www.southernreciperestaurant.com/default.htm
Off to the other side of the world. Specifically a Pakistani-style biryani house. Story Road at Grauwyler, just north of Irving Blvd. There is a place called Aslam Biryani kitchen. They have authentic Pakistani style food. This isn't an Indian restaurant, they serve beef here, lots of beef. Beef biryani, beef haleem, beef nihari, etc. Very meat heavy, very ghee(clarified butter) heavy, as is typical of Pakistani cuisine. They have the best naan I've ever had in Dallas. Light and fluffy, with a crispy underside. You can pull it apart with one hand easily. I've taken lots of co-workers from south Asia here and they all said it's great. The service is a little hit and miss, it's a very family run place, and sometimes that shows.
https://www.facebook.com/pages/Aslam...284465?sk=info
The photos on their Facebook page show their weekend brunch buffet. They're not normally a buffet place, you have to order from the menu most of the time. They also have odd hours during Ramadan.