I'm waiting to hear of someone opening an exchange or somehow facilitating people selling bitcoins in Mexico for MXN, especially as it's now so easy to buy them with USD in the States
Mexico, one of the best documented examples of migration and remittances, received remittance inflows of almost 24 Billion US$ in 2007
Other big markets from http://en.wikipedia.org/wiki/Remittance
Today’s African Diaspora consists of approximately 20 to 30 million adults, who send about USD 40 billion annually to their families and local communities back home.
India received 55 Billion US$ in 2010 & China 51 Billion US$ in 2010.