{
 This Code will return the programs associated with each extension.
 You can obviously modify it to search for a specific extension.
}
 uses Registry;
 procedure TForm1.Button1Click(Sender: TObject);
 var
  reg: TRegistry;
  keys: TStringList;
  i: Integer;
  typename, displayname, server: string;
 begin
  memo1.Clear;
  reg := TRegistry.Create;
  try
  reg.rootkey := HKEY_CLASSES_ROOT;
  if reg.OpenKey('', False) then
  begin
  keys := TStringList.Create;
  try
  reg.GetKeyNames(keys);
  reg.CloseKey;
  {memo1.lines.addstrings(keys);}
  for i := 0 to keys.Count - 1 do
  begin
  if keys[i][1] = '.' then
  begin
  {this is an extension, get its typename}
  if reg.OpenKey(keys[i], False) then
  begin
  typename := reg.ReadString('');
  reg.CloseKey;
  if typename <> '' then
  begin
  if reg.OpenKey(typename, False) then
  begin
  displayname := reg.ReadString('');
  reg.CloseKey;
  end;
  if reg.OpenKey(typename + '\shell\open\command', False) then
  begin
  server := reg.ReadString('');
  memo1.Lines.Add(Format('Extension: "%s", Typename: "%s", Displayname:"%s"' +
  #13#10' Server: %s',
  [keys[i], typename, displayname, server]));
  reg.CloseKey;
  end;
  end;
  end;
  end;
  end;
  finally
  keys.Free;
  end;
  end;
  finally
  reg.Free
  end;
 end;