Two Organizations accepting donations for Chiapas:

1) Enlace Civil
San Cristobal Las Casas Chiapas
Contact Mercedes Osuna at enlacecivil@laneta.apc.org for details

2) Mexico Solidarity Network
Making tax-deductible checks payable to Mexico Solidarity Network,
1247 E. ST., SE, Washington DC 20003
Phone: 773-583-7728 and 202-544-9355

You have to specify if the donation is made for:

a) affected people because of the flooding, or
b) those living in refugee areas due to the political conflict.