<map lat='47.379056950776324' lng='8.524703979492188' zoom='12' view='3' float='right' height='400' width='350'/> Zürich is one of the bigger cities in Switzerland.
The most direct option is to go to the petrol stations on the motorway by train and then foot. If you take the the S12 (to Kilwangen-Spreitenbach), you will be near the service station. One can also use this petrol station to go east and south of Zürich by using the opposite side to the Bern/Basel exit.
The bus station Sportweg makes a great hitchhiking spot. It's located right at the motorway entrance, but there's a traffic light, so cars are not too fast. You can either go there directly by bus, or take a tram to Hardturm from where it's five minutes walking.
There are also many S-Bahn trains stopping at the train station Hardbrücke. (Or take bus #33 and #72, whose first stop after Hardbrücke is Pfingstweidstrasse or bus #54 to Sportweg). When you take a train, walk up onto the bridge on the side closer to the city/main station, then turn right and go down the pedestrians ramp, then straight until you reach the main road Pfingstweidstrasse. Turn left, cross the street. You can already start hitching here, there's enough space and cars, or you can walk closer towards the highway. Or walk and hitch together. It's an excellent street. (update): As of June 2009, 'pfingstweidstrasse' is all under construction and thus nearly impossible to get a ride from.
Direction South (Italy)
If you are trying to go south from Zurich (toward Italy), follow signs in the city for the 4 motorway to Luzern. you will get onto West st. on West, just past the intersection of West and Werd, there is a driveway in front of an apartment building where cars can pull over just before the right turn to the onramp of the 4 motorway. 3 of us got a ride from there within a half hour that took us all the way to Milan, Italy.