Cranes are now a (permanent?) feature of the San Francisco skyline. It's because of all the construction!
If you're ever in a car coming to SF across the Bay Bridge or coming into the city from the south on a highway, you can play "count the cranes" and see how many you get! If you compare month to month, I bet there will be more
If you want to build a luxury high rise residential tower and need a crane, you can get one at businesses like Skyscraper Crane & Rigging.
A project of sadness.
To add a crane to the list below, either find the entry for the building/construction project in question and add the tag "crane" or create a new entry for it and tag it "crane." It's ok if you don't know what to call the entry (you can even say "construction at corner of street x and y". You can also go to the map of San Francisco and hit the button for "Add new map" - this will let you create an entry by dropping a point on the map.