gistfile1.cs

public async void PrintLinksFromMSDNAsync()
{
    var wc = new WebClient()
    var response = await wc.DownloadStringTaskAsync("http://msdn.microsoft.com/pt-br/");
    var regex = "href\\s*=\\s*(?:\"(?[^\"]*)\"|(?\\S+))";
    var matches = Regex.Matches(response, regex);

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