for Donair I like K.O.D. (King of Donair) it's down on Pizza corner, with Sicilian and European, mind you Sicilian makes a good donair as well.
Pogues Fodo is decent and fairly quick if you're not waiting on a large group lunch time.
The Opa is a good greek resturant just a block down from Pizza Corner on Argyle.
If you're close to Spring Garden, Peel Pub - Your Father's Mustache are good places to get some food.
.... wait do you mean downtown Halifax or Calgary