I have been using a new browser on my Apple Mac - Camino. It is much faster than Firefox, yet runs the same rendering engine - Gecko, that powers several browsers including Netscape 8, SeaMonkey, yet unlike Firefox has been designed from the ground up to be an application that has tight Mac integration, so that features available to Mac users such as Spotlight, Keychain & The Address Book work with the browser.
It is interesting to see the Gecko rendering engine, being used in different browsers on different operating systems. This is a good thing as it ensures that no matter what operating system you are using, a website will look the same, work in the same way and be designed to work with the current internet standards.
If you have an Apple Mac then give Camino a go - it is much better than Firefox on the Mac. The only thing you will miss is having a sidebar, which is no great loss because it gives you maximum screen width for when you are browsing very wide sites.