According to the World Bank, more than 215 million people (3% of the world’s population) live outside their countries of birth. Remittances, the money sent home by migrants, are three times the size of official development assistance and they provide an important lifeline for millions of poor households. Remittances to developing countries are estimated to have reached $325 billion in 2010. The overall economic gains from international migration for sending countries, receiving countries, and the migrants themselves are substantial.
Also have a look at these articles published in July 2011:
Football in Brazil: The bountiful game, The Economist, 21 July 2011
The Philippines and remittances: The house that Saud built, The Economist, 21 July 2011