The Federal Emergency Management Agency has an excellent website as a resource for those affected by the Gulf Oil Spill. Disasterassistance.gov is complete with information about filing a claim with BP.
There is also links to resources for small businesses seeking Small Business Administration assistance. "The National Incident Command has established the Deepwater Integrated Services Team to coordinate interagency support services for individuals and small businesses impacted by the BP oil spill - designed to provide residents with full, streamlined access to all federal assistance programs. This includes direct interaction with individuals affected by the spill, facilitation of SBA economic injury assistance loans, and leveraging of existing non-federal services and providers in the Gulf region."
If your business is in one of the affected states these are resources you will want to review.