In Germany different places offer side jobs for students. Most regional employment agencies have job opportunities for students. In large university cities, such as Berlin, the Studentenwerk or the students themselves run job agencies.
Often jobs are advertised on the notice boards at the universities. Most university websites and Studentenwerke have a job market on their website. What is more, all regional or local newspapers have an appointments section where vacant positions are advertised.
Jobs are also advertised on the website of the Federal Employment Agency!