There are three restaurants in Ottawa I really really like. A quick warning is that my parents (who live in Ottawa) go to the first two very regularly, so have regular status... so my experience might not be yours, at least at first.
The first is called the Vietnamese Kitchen, it's on Bank street, near Catherine (exact address is in the phone book... sorry). They are a really inexpensive place (it's easy to eat for under $10 after tax, tip) and have delivery. The service is a little slow, and not everything is uniformly good... but if you like spicy food the Singapore Vermicelli is out of this world. I am drooling now thinking about it. Order it extra spicy if you can. It's so good. Another favourite of mine is a dish with bean curd skin wrapped around vegetarian filling. It's on their vegetarian menu.
The second is the Island Jerk. It's a Jamaican place, also on Bank, but down past Billings Bridge. They have some really good food... their jerk ribs, oxtail and callaloo and codfish are my favourites. The soups are really good too. The food is around $10-12/entree, and plentiful! One of their plates should feed 1.5 me... though I always end up eating it all, it's so good. They have a take-out operation next door (which is how they started actually) and you can buy jerk chicken by the pound.
The third is called Tajin (or something similar in spelling... I'd seen the dish spelled tagine before, so I'm now confused). It's a North African place. I believe it's on Preston street, but I am not entirely sure -- again, the phone book is a good place to look. I've only been there once, so I may have been very lucky. In any case they have a really unusual pastry appetizer that mixes sweet and salty in a subtle, exotic way. I ate there over a month ago, so I am not going to try to describe it, but you really should taste it. They did a brilliant job with their couscous (just heaping high with lamb, mergez and chicken). We finished up with mint tea (made from fresh mint) and a nice dessert (the one with the shredded wheat "hair" on top). I'm guessing that the meal cost around $20/person, though since I wasn't paying and never saw a menu (the waiter/chef? [his apron was dirty with some of the ingredients we later saw in our food, so...] came and suggested stuff, and we said yes), I can't say for sure.