El Castillito, San Francisco
This is probably one of my top 10 burrito places. It was also voted "Citybest," and it's super cheap. This burrito feeds two and costs ~$7.00. I tried to photograph the plastic utensil to give you sense of scale of how big the burrito is. You can look the address on Citysearch, but it's on Mission Street. Take the F, and when you see a Safeway, get off that stop.