string gooRankingUrl = "http://ranking.goo.ne.jp/rss/keyword/keyrank_all1/index.rdf";
XDocument feedXML = XDocument.Load(gooRankingUrl);

XNamespace d = "http://purl.org/rss/1.0/";
XNamespace dc = "http://purl.org/dc/elements/1.1/";

var res = from item in feedXML.Descendants(d + "item")
          select new
          {
              Title = item.Element(d + "title").Value,
              Link = item.Element(d + "link").Value,
              PubDate = (item.Element(dc + "date").Value ?? ""),
              Publisher = (item.Element(dc + "publisher").Value ?? ""),
              Rank = (item.Element(dc + "rank").Value ?? ""),
              Point = (item.Element(dc + "point").Value ?? ""),
              Arrow = (item.Element(dc + "arrow").Value ?? ""),
              Description = (item.Element(d + "description").Value ?? ""),
              Guid = item.Element(d + "link").Value
          };

GridView1.DataSource = res;
GridView1.DataBind();

結果は、こんな感じ。