Walt Mossberg reviews the other browsers at Personal Technology.
Several of these alternate browsers have a very cool feature to which I have recently become addicted: tabbed browsing. With tabbed browsing, you can keep multiple Web pages open at the same time, on the same screen. Only one page is visible at a time, but the others are identified by a row of tabs, usually at the top of the screen. To switch screens, you just click on one of the tabs. The new page appears instantly, because it has already been downloaded.
Tabbed browsing is the biggest fundamental improvement in the Web browser in years.