a shameless plug for the coworking space my company uses, the Port Workspaces [1]. there are a ton of startups in here; tech, nonprofits & more. it's a huge, awesome, quirky space (used to be a mall years ago), just around the corner from Pandora, easily walkable from Bart, close to the lake & uptown/nightlife.

[1] http://portworkspaces.com