The Internet is a great place to look at things you can't have, and this clever map that cross indexes San Franscico real estate listings with location fits snugly in that category. At least the nicer districts do.
The "Median Rent" map by Stephanie May takes a half-year's worth of listing data, and boils it down into the most basic unit of info you could need: the median price of a one bedroom apartment. Slapped on top of an open-source MapBox base, that map also handily dishes out a "suggested" income to survive in any of its little quadrants, the darker the more expensive.
And if you're looking for a real estate cheat-code, just go ahead and settle right in Golden Gate park, by far the most affordable, if probably not a super realistic option. Now if only we could get a version for some other cities we could get a nice, colorful picture of all the sweet 'hoods we shouldn't bother looking at.