I just recently moved to San Francisco, and for the "Housing" section, I highly recommend mentioning "Padmapper" (web app & mobile app) to quickly navigate all the different Airbnb and Craigslist listings in one place.

They have a great map-based UI that easily lets you see how many listings are available where and for how much, and you can easily filter by price, type of stay, # of bedrooms/bathrooms, etc.