Get coffee at Four Barrel, Ritual, Sightglass, Blue Bottle, Philz
Get tacos in the Missions at Taqueria Vallarta, Taqueria Cancun
Go to Noisebridge, Sudo Room, Hacker Dojo
Hike at Hawk Hill, Skeggs, Muir Woods, Mt. Tam
Look up local concerts at funcheapsf.com. There's so many fantastic gargage bands that should have record deals. $5 can get you an amazing show
Have a picnic at Lake Merrit
Walk around some of the university campuses (I quite like Berkeley)
Look at the street art on Clarion Alley
Go to Nightlife at the California Academy of Sciences
To the Conservatory of Flowers
Drive up Twin Peaks on a foggy day and watch Carl roll over the city
Walk around Haight-Ashbury (possibly buy drugs) and check out the shops and food
Walk around Telegraph Ave in Berkeley (possibly buy drugs) and check out the shops and food
Drive CA-1 to Monterey. Stop in Santa Cruz.