For the ultimate takeout super burrito, you might want to try La Tapitia on Grand Ave. in So. San Francisco. It's a Mexican market with a takeout taqueria in the back that makes everything scratch, including the tortillas.
When I worked in the area, one of my favorite lunch spots was Innya Lake on San Mateo Ave. in San Bruno (just across the freeway from the airport exit). Excellent catfish curry soup and spicy dry-fried string beans.
586 San Mateo Ave, San Bruno, CA 94066
La Tapatia Mexicatessen
411 Grand Ave, South San Francisco, CA 94080
As long as we're talking about San Mateo:
B Street probably has the best concentration restaurants anywhere. Lots of accessible parking, and just 2 minutes off the freeway, 5 min from the airport w/out traffic.
My new favorite is B Street & Vine, the bruschetta plate is a great deal.
Here are a few more ideas.
Grand Ave near the airport has a number of decent restaurants some of which have been mentioned. None of them are fancy. I like El Charro mainly because there are a few Bolivian dishes on the menu. They also make a nice margarita.
The Wine Vault doesn't have food other than a special monthly schedule, but they do have wine tasting. I haven't made it there yet.
Another place I want to try that is new is a small Brazilian restaurant called Cafe di Casa.
If you like chinese, consider TMM Deserts on Millbrae Ave, just off 101 (you can't get much closer to the airport). It's not just desserts: they have a full, HK-style cafe menu. I've had several of their soup noodle dishes, along with a steamed-milk custard thing, and they were all quite good.
And I second the Basque Cultural Center.
350 Adrian Rd, Millbrae, CA
Basque Cultural Center's a good value and the only family-style Basque place left in the area (though you don't have to order family-style).
Also in SSF: Villa Del Sol, a good Argentine parrillada, and Bertolucci's, old-school Italian-American.
Basque Cultural Center
599 Railroad Ave, South San Francisco, CA 94080
Villa Del Sol Argentinian
423 Grand Ave, South San Francisco, CA 94080
Sodini's Bertoluccis Ristorante
421 Cypress Avenue, South San Francisco, CA 94080