Flock is a new web browser and works on Windows, MAC and Linux. I’ve not really tried it yet as I’m pretty comfortable with Firefox, however, it seems to have some interesting integration features. In fact, they call it ‘the social web browser’ and it has inter-connectivity with a lot of the popular networking services (eg. Facebook, Flickr, Twitter, YouTube, etc.). It also has extensions similar to Firefox (though I’m guessing its not as extensive currently).