Looking for good Burritos
La Chilenita is good, cheap and filling.
64 Marie-Anne West (between Clark and St-Laurent Boulevard.) There is another location (which Chowhound automatically tagged) but I haven't been there, so I'm not sure if it's as good ;) Not QUITE as convenient to get to from McGill in the winter, but an easy pass through Jeanne Mance Park during the summer.
152 Rue Napoleon, Montreal, QC H2W, CA