Topography aware route planning
Google maps tries to do this in biking mode to begin with: http://googleblog.blogspot.com/2010/03/biking-directions-added-to-google-maps.html

Mapquest is also hill aware to some extent: http://blog.mapquest.com/2011/04/21/cycle-route-planner-aerial-languages/ (I have tried this, but I don't think its particularly great. But I haven't tried it in SF).

Specific to SF, but http://amarpai.com/bikemap/ exists. http://bikesy.com/ is another SF specific one. 

http://veloroutes.org/bikemaps/ isn't directions, but gives you topographical information.