here). But doing something that is your skill and using it to promote a relief effort should not be sniffed at. Designers' skills are not in need directly (I've never felt more useless as a designer), so perhaps its good to simply do what you can.
Font Aid is an already established process which gets designers to contribute a glyph to a font which is then sold to raise money – for Japan in its latest effort.
Meanwhile, the Japanese Red Cross – established, active, required by government to help out in disaster situations and also taking your donations and giving money directly – seems a good place to donate if you want to give without buying something.