While it's not totally cajun, Big T's across from McMahon is all southern inspired. They've got catfish, shrimp, adouille sausage and the such, but their best stuff is the brisket and pork etc...the texas BBQ stuff.
I give it two thumbs up, my whole family loves eating there, especially with the platters (which are awesome).
You can find more info and a menu here:
http://www.urbanspoon.com/r/15/19014...Ts-BBQ-Calgary