Go to

http://bugmenot.com/

and type the URL of the website you want to log into.
Examples:

http://www.nytimes.com/ , http://www.winnetmag.com/

etcetera.

Another (and better) way is changing the user agent of your browser to:
Googlebot/2.1+

http://www.googlebot.com/bot.html

This is very easy in Mozilla’s Firefox. Download and install the User Agent Switcher from

-http://www.chrispederick.com/work/firefox/useragentswitcher/
and add the Googlebot user agent.