To be honest, ive only ever noticed them on one site, and that just has to be the one i need to authenticate on ;-)(
to see the code - view the source of this URL, or run teh code below (probly best not to hammer that server though - its not mine)
$b = new sfWebBrowser(array(), 'sfCurlAdapter');
$b->get('http://ematrix.genusvs.co.uk/login.aspx');
$res = $b->getResponseText();
print $res;
...
<input type="submit" name="Login1$btnLogin" value="Login" id="Login1_btnLogin" class="input-button" />
...
to authenticate I'm using.
$b->get('http://ematrix.genusvs.co.uk/login.aspx')
->setField('Login1$UserName?', 'MYUSERNAME')
->setField('Login1$Password', 'MYPASSWORD')
->click('Login1$btnLogin');
I've also tried.
$b->get('http://ematrix.genusvs.co.uk/login.aspx')
->setField('Login1\$UserName?', 'MYUSERNAME')
->setField('Login1\$Password', 'MYPASSWORD')
->click('Login1\$btnLogin');
but cant find an escaping strategy that works