Here's a message from worldmusic.net:

In the month of January, with any online purchase of any of the following Rough Guides: the Rough Guide to the Music of Thailand, the Rough Guide to the Music of Indonesia, the Rough Guide to the Music of India and the Rough Guide to the Music of the Indian Ocean, World Music Network (UK) will donate £5.00 (about $9.00) from the sale to the Oxfam Tsunami Crisis Fund.

I believe this only refers to purchases made on their site. These are good collections, so this is a no-brainer if you don't already own them. You can get more information and buy the CDs here.