What kind of place are you looking for?
I live in the area and I usually go for takeout from Gol (Iranian food on Spring Garden), bar burrito, shwarma max, or quiznos. Gol is pretty good value I find, It's around $6 for two koobideh kebabs and a lot of rice, and a pop.
I've had lunch a few times at the Indian restaurant that's just north of the Frog & Firkin. It was reasonably priced, tasty, buffet style Indian food. I found that they were always slow to bring around more water even though the restaurant is usually empty besides our table.
I've been meaning to try out Memphis Style smokehouse that's in the same block as Second Cup and Bar Burrito.
There's also all the chain restaurants around, the keg, spring rolls, baton rouge, moxies, boston pizza, and milestones. I've always found spring rolls a convenient place to take a date.
Breakfast options are pretty limited. I usually stick to the Frog&Firkin for breakfast on the weekends. The only other places I can think of that serve breakfast are the Mirage cafe in the sheppard centre, or the Black Sheep pub. I'd avoid the black sheep, the food has always been pretty soggy and gross there in my experience.
I'm also curious to hear any recommendations for yonge and sheppard. I usually like cheap and tasty over more expensive fine dining options. You could also try searching on chowhound for recommendations. Those people know their food better than I do.