Google, as always, was the first to respond with a Google Person Finder for Japan. There is now a full Google Crisis Response page for the earthquake and tsunami, which is full of extensive resources for those in Japan, those trying to contact friends and family in Japan, or for people who want to help out by donating money to the Japanese Red Cross Society. Google has already updated its satellite imagery to show the to-scale effects of the disaster.
Apple was next on the scene, giving iTunes users the ability to donate money directly to the American Red Cross (which is different from the Japanese one!) There doesn't seem to be much else coming out of Cupertino, though, probably because of the impending worldwide release of iPad 2.
Microsoft published a similar 'crisis response' page on its Corporate Citizenship site. Microsoft is working on a "cloud-based disaster response communications portal, based on Windows Azure," which will hopefully help improve government and nonprofit communication with agencies and citizens. Microsoft says it's also giving out temporary licenses to "all impacted customers and partners as well as lead governments, nonprofit partners and institutions involved in disaster response efforts." All in all, though, Microsoft's page doesn't include a whole lot of useful data.
Finally, the Bing department at Microsoft got it a bit wrong by offering $1 for every @bing retweet of Microsoft's Corporate Citizenship site. It wasn't long before comedian Michael Ian Black accused Bing of cashing in on the Japanese tragedy. A few hours later, Bing apologized and said that $100,000 had been donated.