I've been playing with different browsers for the last couple of weeks (Safari, Flock, Firefox, Mozilla, Opera, iCab), and kept coming back to Safari because it just plain "feels" right. The other apps feel ported, in some parts poorly. Then, Les Orchard reminded me of OmniWeb. I've always loved OmniWeb, but the rendering engine was lacking in older versions, and the recent version switched to a custom WebKit framework which works quite well.
OmniWeb 5 has a lot of really nice features. The tab implementation is simply second to none. The app behaves as a first-class citizen on MacOSX. It's got some handy stuff like a tearable textarea widget (so you can hit a button and the textarea box becomes its own window, with resize controls, and export/import functions). The source view rocks, too (with live editing as well), and it's got a decent built-in adblocker.
And, it also offers bookmark syncing via WebDav! (note: U of C webdav info) I'm going to give it a shot as a default browser for awhile...
Here's a screenshot of the textarea widget from the WordPress post entry screen, with the "torn off" windowed version as well: