How does nerdinner show map?

I want to show few countries m开发者_StackOverflow社区arked with "pin" much like what the nerddinner has:

http://nerddinner.com/

How can I achieve this functionality? Any details?

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For detail you can check out this article : Show Your Data on Google Map using C# and JavaScript which provide little info about google map api which help you to achieve your task.