San Francisco has lots of new transportation startups. There are many innovative ways to get around the city and/or make some money off of your unused car, bike or parking space.
Warning: some of the links below are referral links that either benefit me, you, or both of us if you sign up.
TrekCrunch.com lets you compare City Carshare and Zipcar (against other modes).
Short Distance Carpooling
Long Distance Carpooling
City CarShare (use member ID 6144 for referral)