Game companies offering donations for Japan tsunami/earthquake relief include (so far):

Highmoon Games: Buy an Oriental Adventures (and some other stuff) for $5, all money goes to the Red Cross. (source)

Dork Storm Press: Dork Covenant for $5, all money goes to the Red Cross. (source)

Arc Dream Publishing: The Unspeakable Oath (quarterly magazine) for $5, all money goes to the Red Cross. (source)

Sword’s Edge Publishing: Bundle of products for $5, all money goes to the Red Cross. (source)

Point of Insanity Game Studio: Bundle of products for $6, all money goes to the Red Cross. (source)

Applied Vectors: Hero Art bundle for $18, all profits go to the Red Cross. (source)

Tsunami Games

Meanwhile, kids can learn more (actually, very little) about tsunamis at the US National Oceanic and Atmospheric Administration website with some free downloadable material, including trivia and board games. (source)