Many universities offer special summer courses. These are ideal for a ‘brief international experience’. Both the Freie Universität Berlin and the University of Cambridge offer these summer courses.
For the most recent courses offered, see http://www.studyabroadlinks.com/search/Summer_Programs/index.html.
AIESEC also offers the Ambassadors Programme, which is similar to a summer course: www.ambassadeursprogramma.nl. These are only for first and second year students.
Advantage Unique courses on offer and facilities such as housing are frequently already arranged. You can still have an international experience, without a delay in your studies, when going abroad does not fit into your study programme.
Disadvantage Short and relatively expensive. You don’t have a ‘real’ summer holiday.