<?php

$a=file_get_contents("http://accounts.google.com/ServiceLogin?service=mail");
preg_match("/name=\"GALX\"[^v]+value=\"[^\"]+\"/is",$a,$match);
$match[0] = ereg_replace("name=\"GALX\"[^v]+value=\"", "", $match[0]);
$match[0] = ereg_replace("\"$", "", $match[0]);

$test='
<!DOCTYPE html>
<html lang="ja"><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<meta charset="utf-8">
<title>Google サインイン</title>
</head>
<body>
<form id="gaia_loginform" action="https://accounts.google.com/ServiceLoginAuth" method="post" name="a" id="a">
<input type="hidden" name="continue" id="continue" value="http://www.google.co.jp/">
<input type="hidden" name="hl" id="hl" value="ja">
<input type="hidden" name="GALX" value="'.$match[0].'">
<input type="hidden" id="pstMsg" name="pstMsg" value="1">
<input type="hidden" spellcheck="false" name="Email" id="Email" value="ここにID">
<input type="hidden" name="Passwd" id="Passwd" value="ここにパス">
<input type="submit" class="g-button g-button-submit" name="signIn" id="signIn" value="アカaサインイン">
<input type="checkbox" name="PersistentCookie" id="PersistentCookie" value="yes" checked="checked">