Career Services posts a variety of interesting and qualifying entry-level jobs, traineeships, and internships for students on its
Job portal (in german only)

In addition to ist own job portal, Career Services offers an
extensive overview of other job portals (in german only)

Besides numerous other things offered or sought there are often good spare-time jobs to be found in the marketplace.
Marketplace UZH

The electronic job bourse of the assistants' association and the association for students undergoing doctoral studies at the ETH Zurich (AVETH) and Lausanne (ACIDE).
ETH get hired

Situations vacant through the Swiss Banking Institute
JobEye

www.jobs.uzh.ch

The student association uniboard Zurich runs on their website uniboard.ch an online-forum «My Career» with job offers for students.
uniboard.ch My Career