Berkeley, CA + Add a trip

If you're a student you can get free wireless nearly everywhere within a couple of blocks of campus through the AirBears system: http://airbears.berkeley.edu/map/

If you're visiting the campus you can get a guest AirBears account for up to one week, just ask a member of staff or faculty very nicely! See http://airbears.berkeley.edu/guestaccounts.shtml

Apart from that I'm sure a lot of cafes have wireless. Berkeley Espresso on Shattuck definitely does, the fact that every table usually contains at least one laptop is a testament to that -- the coffee is much better at Guerilla Cafe up the street but they're too cool to have wireless.