With the terrible tragedy happening in Japan, Apple has made donating to the Red Cross relief fund easy through the use of the itunes store. Donations can be made in amounts of $5, $10, $25, $50, $100 and $200. Apple says that 100% of donations go to the Red Cross.
iTunes donation link is here.
You can also donate on the Red Cross website or text 90999 to do an instant donation of $10.00.