I just landed a job working as a Unix Sysadmin at a small company in the FiDi on Market near 4th.
Problem is, they won't allow bicycles inside the building, so I have to lock up to one of the upside down U racks on the sidewalk on Market, and I didn't feel comfortable doing that with either my fix or my Soma Doublecross.
So, I bought a cruiser. My commute is just from about 7th & Folsom to 4th & Market, so it's pretty much all flat. I got an all matte black Electra "Coaster 1", which is a SS with a coaster brake.
It's actually a really cool, comfortable bike if you're not in a hurry (it's SS and geared really low). Aluminum frame too so it's relatively light and the huge 26" tires give it a good ride in spite of the stiff frame.
It's cheap enough so that if it gets stolen (I do intend to lock it securely, but this is SF), it won't be to big a bummer.