Here's a little code snippet that will search a collection of Controls for the first control of a specified type.

private object FindControlByType( Control root, Type t )
{
  if ( root != null && root.GetType().Equals( t ) )
    return root;
  foreach( Control c in root.Controls )
  {
    object node = FindControlByType( c, t );
    if ( node != null && node.GetType().Equals( t ) )
      return node;
  }
  return null;
}

Example: the following example returns the first instance of an HtmlForm in a Page's Control collection:

HtmlForm form = (HtmlForm) FindControlByType( Page, typeof( HtmlForm ) );