There was an 8.5 earthquake last night with an epi centre near Banda Aceh in Sumatra (BBC News Coverage). Because of the locations proximity to water it caused a massive Tsunami (Wikipedia Coverage).
The areas affected include Indonesia (Sumatra is part of Indonesia), Sri Lanka, India, Thailand, Malaysia, Maldives and Bangladesh. Sri Lanka, Indonesia and India were hardest hit with 3538, 4185 and 2000 respectively.
Update #1: The death toll has now risen to 22,000 (Source: azcentral.com, AP). From the article it says that the waves created raced across the 2,800 miles of the Indian Ocean and hit Africa. So the already suffering citizens of those regions have been dealt a double blow. With so many impacted I wonder what can be done to help.