Sonarrat has the right idea, you can take the 380 to the 280 south, then take Sand Hill Rd to Santa Cruz turn right, and left on Junipero Serra, and left on Campus Dr, (depending on where on campus your going there is Campus Dr. West and Campus Dr. East).
For public transit you can take BART from SFO to San Bruno, transfer at the station to another train to Millbrae, and then take a southbound Caltrain to Palo Alto, where then you can take a Marguerite shuttle to Stanford.
Or you can take the KX bus from SFO to Palo Alto, and then take the Marguerite Shuttle.
Driving:
from:SFO to:I-280 S to:37.421129,-122.20243 to:Running Farm Ln - Google Maps
Public Transit:
from: SFO to: 450 Serra Mall, Stanford, CA 94305 (Stanford University) - Google Maps
BART:
BART - Bay Area Rapid Transit
Caltrain:
caltrain.com - home
SamTrans KX:
http://www.samtrans.org/pdf/Schedule...X_10-10-05.pdf
Marguerite Shuttle:
P&TS - Marguerite Shuttle
Whatever you do DO NOT take a taxi you haven't prearranged to take you from SFO to Stanford, I did that once, and it will cost you at least $90, for 25 miles. SFO taxis have a monopoly on picking up passengers at SFO without direct dispatch, meaning if you want a peninsula based taxi you have to call for one ahead of time. SF taxis will charge you 1.5 times the fare price going to Stanford, that includes airport flag down fee. Seriously at that price you might as well arrange for a Lincoln Town Car to pick you up for $100, you have been warned.