American page, the English page, Australia, New Zealand, and Google is forwarding donations to the Japanese Red Cross here.
You can also donate through Yahoo Japan, and this site has a list of Japanese language charities taking donations for this cause. Time published an article called "Six Ways You Can Help Victims in Japan"
You can see the Japanese Red Cross' relief efforts on their website, and details of giving blood on their Japanese page.
For those living in Japan, as things start to settle down and the rehousing begins there will be a significant need for new or used appliances/home goods. When large-scale collections start we'll post more information.
Up-to-date reports on current quakes and aftershocks are best found on the Japanese MET Agency website.
Google's quake page offers a people finder, transportation news, etc.
A guide has been issued in numerous languages to help you cope with this or future quakes or aftershocks.