I'm trying the new version of Opera right now. So far, it appears to be faster and less resource heavy than Firefox (??! !) and also supports Tabbed browsing.
I remember briefly tring out Opera back in 1998, (Back when it would fit on a 1.4MB Floppy) and I thought that it had some pretty interesting features then, but the GUI was absolutely HORRIBLE!. I also used the Mac Version briefly back in 2k1-2k2, and It had improved greatly, though it still had issues when it came to displaying certain pages. --I think the current version is vastly superior to previous versions, but I'll have to use it a bit more