If you would like to help, Association for India's Development (AID) is raising funds for relief work in Bihar. (On the main page, click on the "All India Relief Relief Fund" link).
MSF has filed a field report on Bihar.
"Some areas remain totally cut off and stories from those in the makeshift camps indicate that entire villages have been destroyed by the floodwaters with no inhabitants surviving. These areas are now starting to face acute food shortages."