If you have not done your part yet, then you can do so from both Amazon and Google , who now have links on how to contribute to the Tsunami relief on their homepages ( here and here respectively). I am not sure what kind of service would be the right one, but I am sure any kind would surely be helpful! I would be doing my bit for sure.
Update: Slashdot also picked up on this and Apple has also changed their homepage.
[Listening to: 01 - Track - New Title (38) (04:36)]