Romania has a huge market for summer jobs. You can work in a vibrant seaside resort, in a scenic mountain resort, or in a historical city in the tourism industry. The best way to find a summer job is by searching for opportunities on the web, check advertisements at your university, check the many student organisations, ask your friends or go directly and speak in the place you would like to work.
Romania has many NGOs who are active in fields such as human rights, environment, social protection, politics, education, etc. and they are in constant need of volunteers for their projects. Ask around or search the web for opportunities!