I just discovered this site via NYT (TimesSelect), in an article about the Mission.
“The Mission is the burrito vortex,” said Charles Hodgkins, who has visited every one of the city’s more than 150 taquerias – nearly a third of them are in the Mission – rating each burrito for his Web site, burritoeater.com. (Taqueria San Francisco, an unassuming neighborhood hole-in-the-wall on 24th Street, boasts the highest-rated burrito in the city.)