Instapundit is running a blogburst that bloggers can ping (and send him an email) stating what charities people can give money to and help with relief efforts. It’s amazing to see the response he’s getting!
One that may not be up there is the Great Hour of Sharing. They’re taking money for relief efforts as well, but I don’t think that fact is posted on their site yet.
Also, if all else fails, you can always contact local churches, Salvation Armies, etc. to see how you can help with the resources that we have.