There are quite a few volunteering organisations, both local and international, that offer programmes in Macau to interested foreigners. The vast majority of these programmes focus on community development. You can volunteer to work with disabled or street children, teach a variety of topics in a local school, or volunteer your medical skills. Other popular projects include helping local organisations.
There are quite a few volunteer agencies offering longer-term programmes, such as 6 months long or one year long projects. Such projects give you a great opportunity to immerse yourself in the local culture and learn a new language, Cantonese. Since flight fares are usually cheap in Macau, you could very well visit the entire Asian region while on your volunteering programme. Agencies also organise a variety of activities for volunteers, such as bungee jumping or hiking.
Most programmes designed for foreigners are organised in English, so proficiency in the language is a must. Knowledge of the Portuguese language might also be appreciated. With most agencies, fees cover the cost of accommodation and meals.
For any programme lasting longer than 3 months, it is best to contact a local embassy for visa requirements.