This is a great news site.  Somewhat lest formal than the government site.  The content is also a little less overwhelming, and somewhat easier to read.  Navigating this site is also very easy and quick.  Although there are no interactive features here, the content is premium. You can find out everything you would want to know about organ donation.  There are also excellent links to other donation sites in the US.

This is an extremely valuable and informative government site with links to signing up and information.  The site is directed at a wide range of people, but is still pretty easy to navigate and read.  It may take you a little time to find exactly what you are looking for, but the information, data and articles are credible and solid.  And excellent overall site.

This is the coalition for Organ donation.  Includes news, info and resources.

An awesome site from PBS with cool resources and graphics.

The main American Red Cross website that gives info, news and donor eligibility guidelines.

Blood donation information from the New York Blood Center.

This site enables you to sign up to make a blood donation at the location and time of your choice. It also has information on donating blood.

An excellent site that has all the general information you need when making the decision to donate.

This is an excellent site with information, how to donate, etc.