Fellow comms blogger Nik Ranken has produced a really useful overview of Geert Hofstede's work on cultural differences.
Culture's Consequences, Hofstede's groundbreaking book on organizational culture, was first published in 1980. It is based on a monumental study of a multinational corporation (IBM) operating in 39 countries. It is essential reading for anyone who wants to know about differences in culture between various countries. It also remains one of the most widely cited works in international management. Nik's blog captures the key points.
You can access Hofstede's own website at http://feweb.uvt.nl/center/hofstede/index.htm.