Feeling adventurous? If so, you can try out the release candidate of the upcoming new version of Firefox, 3.6. The 7.7 MB download will give you a taste of what's to come in this version, and we're talking about some very interesting changes.
Firefox 3.6 runs on the well-tested Gecko 1.9.2 web-rendering platform, bringing support for new web technologies, better speed, stability, faster startup and load times, as well as improved Javascript performance.
As far as new features go, perhaps the most interesting one is Personas, which lets users change the appearance of the browser with one click. Furthermore, the new Firefox will alert you when your plugins are out of date, and, finally, it's optimized for small device operating systems, for example Windows CE and Maemo.