If you look around, you will be able to locate many agencies which habitually take up jobs on behalf of companies. Approach them and leave your bio-data with them, before your vacations. Certain restaurants require people for short durations to meet the summer rush. Identify these in your town and approach them as well. If you want to take part in trade fairs, meet the organizers of such events in your city.
Summer is the time that many exhibitions and fairs are held, and the opportunities are great.
Jobs related to getting opinions about certain products or telemarketing selling things over the telephone are gaining popularity as well. Usually, the agencies that do this work have a database of students and call them once they get the job from a company. So it is important to get on the active list of these agencies. Another way to get summer jobs is through relatives or parents of friends who may be employed in banks and companies. Make your intentions known and give them your biio-data.