uses
 Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
 Dialogs, StdCtrls, ComCtrls, OleCtrls, SHDocVw, MSHTML_TLB;

procedure TForm1.Button1Click(Sender: TObject);
var
v: Variant;
 form : variant;
 f,i:Integer;
 begin
WebBrowser1.Navigate('http://id.rambler.ru/sсriрt/newuser.cgi');

for f:=0 to WebBrowser1.OleObject.Document.forms.Length-1 do begin
form:=WebBrowser1.OleObject.Document.forms.Item(f) .elements;
for i:=0 to form.Length-1 do
if form.item(i).name='login' then 
form.item(i).value:='test1'
else
if form.item(i).name='firstname' then 
form.item(i).value:='test2';

end;  end;