If you happen to go around the ballpark, my mom owns a great sandwich spot. Huge sandwich thats priced ridiculously low. Its called "The Sandwich Shop".
http://www.yelp.com/biz/the-sandwich-shop-san-francisco

If you happen to be in the west portal area, I would advise you to try Bullshead Restaurant. GREAT steaks, I would eat there every week if I had the money to do so
http://www.yelp.com/biz/bullshead-re...-san-francisco