supponendo di avere un datagrid nella pagina...
codice:
    Protected Sub Button1_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles Button1.Click
        Dim result = From f In Directory.EnumerateFiles("c:\tmp")
                     Where
                     Path.GetExtension(f).ToLower = ".doc" OrElse Path.GetExtension(f).ToLower = ".pdf" OrElse Path.GetExtension(f).ToLower = ".rtf" _
                     Select New With {
                         .file = String.Format("{0} ", Path.GetFileName(f))
                     }



        Me.DataGrid1.DataSource = result
        Me.DataGrid1.DataBind()

    End Sub