namespace TestItems
{
  /// <summary>
  /// Descrizione di riepilogo per WebForm1.
  /// </summary>
  public class WebForm1 : System.Web.UI.Page
  {
    protected System.Web.UI.WebControls.DataGrid test;
    protected System.Web.UI.WebControls.Label label;
    private DataSet myDs;
  
    private void Page_Load(object sender, System.EventArgs e)
    {
       myDs = new DataSet();
      DataTable myDt = new DataTable();
      myDt.Columns.Add("lingua", System.Type.GetType("System.String"));
      myDt.Columns.Add("languageID", System.Type.GetType("System.Int32"));
      myDt.Rows.Add(myDt.NewRow());
      myDt.Rows.Add(myDt.NewRow());
      myDt.Rows.Add(myDt.NewRow());
      myDt.Rows.Add(myDt.NewRow());
      myDt.Rows[0][0] = "italiano";
      myDt.Rows[0][1] = 1;
      myDt.Rows[1][0] = "inglese";
      myDt.Rows[1][1] = 2;
      myDt.Rows[2][0] = "spagnolo";
      myDt.Rows[2][1] = 3;
      myDt.Rows[3][0] = "tedesco";
      myDt.Rows[3][1] = 4;
      myDs.Tables.Add(myDt);


      if(  !Page.IsPostBack ) 
      {
      test.DataSource  = myDs;
      test.DataBind();
      }

    }
    private void test_ItemDataBound (object sender, DataGridItemEventArgs e)
    {
      
        if (e.Item.ItemType == ListItemType.Item | e.Item.ItemType == ListItemType.AlternatingItem)
        {
          DropDownList _drop = (DropDownList)e.Item.FindControl("drop");
          _drop.DataSource = myDs;
          _drop.DataTextField = "lingua";
          _drop.DataValueField = "languageID";
          _drop.DataBind();
        }
      
    }
    private void test_ItemCreated (object sender, DataGridItemEventArgs e)
    {
      if (e.Item.ItemType == ListItemType.Item | e.Item.ItemType == ListItemType.AlternatingItem)
      {
        DropDownList _drop = (DropDownList)e.Item.FindControl("drop");
        _drop.SelectedIndexChanged += new EventHandler(_drop_SelectedIndexChanged);
      }

    }
    private void _drop_SelectedIndexChanged(object sender, EventArgs e)
    {
      label.Text = ((DropDownList)sender).ClientID;
    }

    #region Codice generato da Progettazione Web Form
    override protected void OnInit(EventArgs e)
    {
      InitializeComponent();
      base.OnInit(e);
    }
    
    private void InitializeComponent()
    {    
      this.Load += new System.EventHandler(this.Page_Load);
      this.test.ItemDataBound += new DataGridItemEventHandler(test_ItemDataBound);
      this.test.ItemCreated += new DataGridItemEventHandler(test_ItemCreated);

    }
    #endregion
  }
}

<form id="Form1" method="post" runat="server">
      <asp:DataGrid ID="test" Runat="server" AutoGenerateColumns="False">
        <Columns>
          <asp:TemplateColumn>
            <ItemTemplate>
              <asp:DropDownList Runat="server" ID="drop" AutoPostBack="True"></asp:DropDownList>
            </ItemTemplate>
          </asp:TemplateColumn>
        </Columns>
      </asp:DataGrid>
       <asp:Label Runat="server" id="label"></asp:Label>
    </form>