gistfile1.cs

public void PrintLinksFromMSDNWithContinuation2()
{
    var wc = new WebClient();
    wc.DownloadStringCompleted += (sender, e) =>
        {
            var regex = "href\\s*=\\s*(?:\"(?[^\"]*)\"|(?\\S+))";
            var matches = Regex.Matches(e.Result, regex);

            foreach (Match match in matches)
                Console.WriteLine(match.Groups[1]);
        };

    wc.DownloadStringAsync(new Uri("http://msdn.microsoft.com/pt-br/"));
}