public static DateTime GetLastDumpDate(string wiki)
        {
            string directoryListing = null;

            while (directoryListing == null)
            {
                try
                {
                    directoryListing = WC.DownloadString(DumpsUrl + wiki + '/');
                }
                catch (Exception e)
                {
                    Console.WriteLine(e);
                }
            }
            directoryListing = directoryListing.Replace(" ", " ");

            XNamespace ns = "http://www.w3.org/1999/xhtml";

            // to make sure DTDs are not downloaded
            var xmlReader = XmlReader.Create(
                new StringReader(directoryListing),
                new XmlReaderSettings {
                XmlResolver = null, DtdProcessing = DtdProcessing.Ignore
            });

            XDocument doc = XDocument.Load(xmlReader);

            return((from elem in doc.Descendants(ns + "a")
                    select DateTimeExtensions.ParseDate(elem.Value)
                    into date
                    where date != null
                    select date.Value).Max());
        }