Airline & Travel:
www.cheaptickets.com
www.expedia.com
www.hotwire.com
www.jetblue.com (into Oakland only)

Local Transportation:
www.sfgate.com/traveler/guide/transportation/
www.sfmuni.com/home/dhome.htm
www.bart.gov/index.asp

Outdoor/Adventure:
http://areas.wildernet.com/
http://www.kron4.com/

General Information: travel, lodging, restaurants, cultural, etc.
http://sanfrancisco.citysearch.com/
www.sfgate.com/traveler/
www.tripadvisor.com/
www.sfguide.com/