Google China links to a custom search engine for sites that include information about missing persons. Kai-Fu Lee, President of Google China, told Google Blogoscoped: "[Engineering lead Harry Ke] and two other engineers came up with the idea of helping people search for lost relatives or friends. Given there are... tens of thousands still trapped, and some 200,000 wounded, and many more homeless. Also, cell phone and land lines are mostly not working. Transportation is difficult because the disaster area is on mountains and valleys. So, there are many people frantically looking for lost relatives and friends."
There's also a page for offering donations that mentions "Google will donate $2 million, including $1.7 million from Google.org, to help assist in relief and rebuilding efforts". A special Google Earth layer shows recent high-resolution imagery from the areas affected by the earthquake.
{ Thanks, Matthew Chan. }