Just a reminder, Friday September 19 is Park(ing) Day. On the website you'll find a map with at least four Oakland locations. But according to their blog (different from the website), the Nomad Cafe is participating, and they aren't included on the Oakland map, so their may be others. If you know of any, share them in comments.
Meanwhile, it seems you can't swing a stick in central San Francisco without hitting some park(ing). You can find a description of the San Francisco highlights here. Unfortunately, the Oakland description is somewhat confusing.
If you are heading into the City, I highly recommend downloading (1.2 MB) the PDF map of the San Francisco park(ing) locations. It looks like the base is by the folks at Raven Maps, a company that makes maps so beautiful you could cry. If you like what you see, they also make large state maps and benchmark atlases.
Careful though, you may never settle for the graphically-challenged Google maps again. As far as free internet maps go, try Yahoo maps, which are a bit easier on the eyes, though they don't have that cool street view feature.
But I digress, just go park(ing), but don't forget to feed the meter.