The Firefox plugin User Agent Switcher is a quick and dirty way to often get past login requirements on several news sites. By setting the plugin to report that you’re the GoogleBot, you can often view content on sites that would otherwise require a login. This works because sites will allow Google to browse their site freely so all of the content gets indexed for the search engine. However, when you show up, it realizes you’re not Google and forces you to log in or sign up to view the same content.
The plugin is also useful if you’re your checking out how your site handles requests from mobile phones. I set it to report the my browser was a Windows Mobile phone and then used the Mobile Press plugin for WordPress to reformat my blog for mobile phones. This way I could check out how everything was working without having to go back to my phone constantly.