I'll give Toronto this: spacing.ca looks like an interesting snapshot of life in a big city. (and makes me pine for my days at UofT) A recent feature highlighted the paste-up posters you can find on any telephone pole or construction hoarding. On an impulse, a show by "Armed & Hammered" or "Happy Girl Hydroponics" might just be worth it.
Another good site for fine photography of urban graffiti is Satan's Laundromat. Highly worth a visit.