One of the biggest ways you can make an impact right now is by donating money. Although British Petroleum (BP) has pledged to fund all clean-up and rescue efforts, reputable wildlife rescue organizations that are on the front lines could still use help in the form of monetary donations. Organizations like the National Wildlife Federation (NWF) will put your donation toward the long-term rescue of oiled animals, restoration of the wetlands and education in coastal communities to help with spotting and reporting oiled wildlife.
Tri-State Bird Rescue & Research is currently heading the charge in cleaning and rehabilitating oiled animals. Your donation to this group would go toward training and allow them to maintain a fast response to oil spills. Most organizations aren't currently accepting supplies, but Matter of Trust has taken donations of human and pet hair to create booms and mats that help absorb oil. Although the group isn't currently taking new donations, you can sign up to get notified when it begins again.