After I upgraded to 1.5.0.1, I could not access certain sites. One of them said that my browser was too old, and I had to upgrade to at least Firefox 1.0 or Internet Explorer 6.0.
If I only had Opera installed, I could fool the site by switching the User-Agent that is sent with every request. This switch is built-in into Opera, and was quite a cool feature! Firefox doesn’t have this feature out of the box, but halleluja, there is a plugin that solves this!

Check out “User Agent Switcher” by Chris Pederick.
[tags]Mozilla, Firefox, Plugin[/tags]