How can I add links to external web sites in MVC 4?

In MVC, there is no helpers for generating links based on absolute URLS (i.e., to external resources). But you can write your own helper for that if you want the view to look nice with the consistent Helper formatting.

http://www.asp.net/mvc/tutorials/creating-custom-html-helpers-cs

example:
create extension method

public static class LinkHelper
{
	public static string ExternalLink(this HtmlHelper helper, string url, string text)
        {
        	return String.Format("<a href='http://{0}' target="_blank">{1}</a>", url, text);
	}
}

and call this in your view like:

@Html.ExternalLink("www.google.com", "Google")