Sezmu, LuLous (high end)
Dish Cafe (breakfast and lunch for soups, salads, sandwiches, great desserts)
Biscola in the Grand Sierra (rustic Italian)
Big Ed's Alley Inn (very casual, but GOOD steaks, baked potato kind of fare)
El Adobe (Mexican)
Stonehouse (decent dinner, good for breakfast, too)
Those should give you a good start.
Yikes, that's a broad category. Can you help narrow it down?
Sezmu and Fourth Street Bistro are highly recommended restaurants at the upper.
Betos, cash only, is a favorite Mexican joint. Small and informal.
Hiroba sushi is my favorite sushi place. La Vecchia for Italian. Lots of good Thai restaurants. Bangkok Cuisine is probably my favorite. Pegl's Glorified Ham and Eggs (both locations) and Stonehouse Cafe for breakfast. Nu Yalk Pizza and Carrella's Italian Deli for pizza. If you like Persian food and are are looking for kabobs, Parisa's is a small cafe in the Sparks industrial section.
Also El Tumi is a new Peruvian restaurant that opened on Moana Lane and it's a Chowhound type destination.