By now you already know the state of devastation Japan is in. So take the effort and put some money towards helping them rebuild. The easiest ways to donate are by texting the Red Cross (text REDCROSS to 90999 from any mobile to make a $10 USD donation) or instant donations through Paypal.
Here is a list of other reputable charities
Also if you still need something to show for you donation check these out.
Corter Leather bracelet for japan-All proceeds to Red Cross.
Max Erdenberger's Help Japan Poster
Lady Gaga wristband for Japan