There are a number of organizations who specialize in caring for oiled wildlife, and it's safe to say they've got their work cut out for them in the Gulf right now. I know of two, based here in California, who do work world wide. If you know of others, post a comment and I'll add them to the diary.
To report oiled wildlife affected by the Gulf oil spill please call the Wildlife reporting hotline at 1-866-557-1401.
More info below....
One other thing to add: What these organizations will need most right now is money. It costs a lot to pull together their teams of experienced workers and send them to disaster sites - especially when it's likely to be as widespread as this looks to be. They'll ultimately be reimbursed for some of this, but they need money to respond now.
If you do want to get involved as a volunteer, you probably won't start by washing birds. It requires some training and they don't have a lot of time to train while they're responding to the crisis. However, they will need probably need lots of other help - transporting wildlife to treatment centers, cleaning cages, washing dishes, filling feeding tubes, answering phones, washing towels.
The two groups that I know of Oiled Wildlife Care Network - here's their donation page.
and
International Bird Rescue Research Center (donation link at top right on the home page). They already have team on the way to the gulf. One other message from their site:
IBRRC has been receiving an outpouring of support and phone calls from people wishing to volunteer to help at the Gulf Oil Spill. To learn how to help, you must contact the BP Community Support Team Hotline at 1-866-448-5816.
Again, to report oiled wildlife, call 866-557-1401.
Per swizzle, more contact info:
... to contact the response teams to report oiled or injured wildlife at, 800-557-1401 and have set-up a toll-free number for Volunteers to call, 866-448-5816