Vespa Lunch (do I have that right? I've never been in that place sober/non-high), Golden Griddle, and Papa Ceo's on Spadina, which is open till 4:00 am or something.
Been to Insomnia a few times. Indeed they are open late, play some pretty decent music and have some internet stations as well. I've never tried the food, but they have a very large bar with an incredible drink selection. One of the better places in T.O. for martinis if that's your thing.
Also go to insomnia quite a lot... the food is very good for a place that serves till 4 am. The ambiance is always great on weekends with good djs and an eclectic late night post bar crowd. If you want a great chocolate dessert try the one they call climax.....
A lesbian friend of mine ( :smokin ) mentioned to me that a cafe/bistro on Church St. is open 24hrs from Fri>Sun. I think it's called BLU. I drove past it one night and it looked cool. It was all orange! haha... j/k. It was blue.